c assignment operator with different types

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1. Simple Assignment Operator (=)

Example of simple assignment operator.

2. Compound Assignment Operators


+=	addition assignment	It adds the right operand to the left operand and assigns the result to the left operand.
-=	subtraction assignment	It subtracts the right operand from the left operand and assigns the result to the left operand.
*=	multiplication assignment	It multiplies the right operand with the left operand and assigns the result to the left operand
/=	division assignment	It divides the left operand with the right operand and assigns the result to the left operand.
%=	modulo assignment	It takes modulus using two operands and assigns the result to the left operand.

Example of Augmented Arithmetic and Assignment Operators


&=	bitwise AND assignment	It performs the bitwise AND operation on the variable with the value on the right
\|=	bitwise OR assignment	It performs the bitwise OR operation on the variable with the value on the right
^=	bitwise XOR assignment	It performs the bitwise XOR operation on the variable with the value on the right
<<=	bitwise left shift assignment	Shifts the bits of the variable to the left by the value on the right
>>=	bitwise right shift assignment	Shifts the bits of the variable to the right by the value on the right

Example of Augmented Bitwise and Assignment Operators

Practice problems on assignment operators in c, 1. what will the value of "x" be after the execution of the following code, 2. after executing the following code, what is the value of the number variable, benefits of using assignment operators, best practices and tips for using the assignment operator, live classes schedule.

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Assignment Operators in C

In C language, the assignment operator stores a certain value in an already declared variable. A variable in C can be assigned the value in the form of a literal, another variable, or an expression.

The value to be assigned forms the right-hand operand, whereas the variable to be assigned should be the operand to the left of the " = " symbol, which is defined as a simple assignment operator in C.

In addition, C has several augmented assignment operators.

The following table lists the assignment operators supported by the C language −

Operator	Description	Example
=	Simple assignment operator. Assigns values from right side operands to left side operand	C = A + B will assign the value of A + B to C
+=	Add AND assignment operator. It adds the right operand to the left operand and assign the result to the left operand.	C += A is equivalent to C = C + A
-=	Subtract AND assignment operator. It subtracts the right operand from the left operand and assigns the result to the left operand.	C -= A is equivalent to C = C - A
*=	Multiply AND assignment operator. It multiplies the right operand with the left operand and assigns the result to the left operand.	C = A is equivalent to C = C A
/=	Divide AND assignment operator. It divides the left operand with the right operand and assigns the result to the left operand.	C /= A is equivalent to C = C / A
%=	Modulus AND assignment operator. It takes modulus using two operands and assigns the result to the left operand.	C %= A is equivalent to C = C % A
<<=	Left shift AND assignment operator.	C <<= 2 is same as C = C << 2
>>=	Right shift AND assignment operator.	C >>= 2 is same as C = C >> 2
&=	Bitwise AND assignment operator.	C &= 2 is same as C = C & 2
^=	Bitwise exclusive OR and assignment operator.	C ^= 2 is same as C = C ^ 2
\|=	Bitwise inclusive OR and assignment operator.	C \|= 2 is same as C = C \| 2

Simple Assignment Operator (=)

The = operator is one of the most frequently used operators in C. As per the ANSI C standard, all the variables must be declared in the beginning. Variable declaration after the first processing statement is not allowed.

You can declare a variable to be assigned a value later in the code, or you can initialize it at the time of declaration.

You can use a literal, another variable, or an expression in the assignment statement.

Once a variable of a certain type is declared, it cannot be assigned a value of any other type. In such a case the C compiler reports a type mismatch error.

In C, the expressions that refer to a memory location are called "lvalue" expressions. A lvalue may appear as either the left-hand or right-hand side of an assignment.

On the other hand, the term rvalue refers to a data value that is stored at some address in memory. A rvalue is an expression that cannot have a value assigned to it which means an rvalue may appear on the right-hand side but not on the left-hand side of an assignment.

Variables are lvalues and so they may appear on the left-hand side of an assignment. Numeric literals are rvalues and so they may not be assigned and cannot appear on the left-hand side. Take a look at the following valid and invalid statements −

Augmented Assignment Operators

In addition to the = operator, C allows you to combine arithmetic and bitwise operators with the = symbol to form augmented or compound assignment operator. The augmented operators offer a convenient shortcut for combining arithmetic or bitwise operation with assignment.

For example, the expression "a += b" has the same effect of performing "a + b" first and then assigning the result back to the variable "a".

Run the code and check its output −

Similarly, the expression "a <<= b" has the same effect of performing "a << b" first and then assigning the result back to the variable "a".

Here is a C program that demonstrates the use of assignment operators in C −

When you compile and execute the above program, it will produce the following result −

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Assignment operator in c.

Last Updated on June 23, 2023 by Prepbytes

c assignment operator with different types

This type of operator is employed for transforming and assigning values to variables within an operation. In an assignment operation, the right side represents a value, while the left side corresponds to a variable. It is essential that the value on the right side has the same data type as the variable on the left side. If this requirement is not fulfilled, the compiler will issue an error.

What is Assignment Operator in C language?

In C, the assignment operator serves the purpose of assigning a value to a variable. It is denoted by the equals sign (=) and plays a vital role in storing data within variables for further utilization in code. When using the assignment operator, the value present on the right-hand side is assigned to the variable on the left-hand side. This fundamental operation allows developers to store and manipulate data effectively throughout their programs.

Example of Assignment Operator in C

For example, consider the following line of code:

Types of Assignment Operators in C

Here is a list of the assignment operators that you can find in the C language:

Simple assignment operator (=): This is the basic assignment operator, which assigns the value on the right-hand side to the variable on the left-hand side.

Addition assignment operator (+=): This operator adds the value on the right-hand side to the variable on the left-hand side and assigns the result back to the variable.

x += 3; // Equivalent to x = x + 3; (adds 3 to the current value of "x" and assigns the result back to "x")

Subtraction assignment operator (-=): This operator subtracts the value on the right-hand side from the variable on the left-hand side and assigns the result back to the variable.

x -= 4; // Equivalent to x = x – 4; (subtracts 4 from the current value of "x" and assigns the result back to "x")

* Multiplication assignment operator ( =):** This operator multiplies the value on the right-hand side with the variable on the left-hand side and assigns the result back to the variable.

x = 2; // Equivalent to x = x 2; (multiplies the current value of "x" by 2 and assigns the result back to "x")

Division assignment operator (/=): This operator divides the variable on the left-hand side by the value on the right-hand side and assigns the result back to the variable.

x /= 2; // Equivalent to x = x / 2; (divides the current value of "x" by 2 and assigns the result back to "x")

Bitwise AND assignment (&=): The bitwise AND assignment operator "&=" performs a bitwise AND operation between the value on the left-hand side and the value on the right-hand side. It then assigns the result back to the left-hand side variable.

x &= 3; // Binary: 0011 // After bitwise AND assignment: x = 1 (Binary: 0001)

Bitwise OR assignment (|=): The bitwise OR assignment operator "|=" performs a bitwise OR operation between the value on the left-hand side and the value on the right-hand side. It then assigns the result back to the left-hand side variable.

x |= 3; // Binary: 0011 // After bitwise OR assignment: x = 7 (Binary: 0111)

Bitwise XOR assignment (^=): The bitwise XOR assignment operator "^=" performs a bitwise XOR operation between the value on the left-hand side and the value on the right-hand side. It then assigns the result back to the left-hand side variable.

x ^= 3; // Binary: 0011 // After bitwise XOR assignment: x = 6 (Binary: 0110)

Left shift assignment (<<=): The left shift assignment operator "<<=" shifts the bits of the value on the left-hand side to the left by the number of positions specified by the value on the right-hand side. It then assigns the result back to the left-hand side variable.

x <<= 2; // Binary: 010100 (Shifted left by 2 positions) // After left shift assignment: x = 20 (Binary: 10100)

Right shift assignment (>>=): The right shift assignment operator ">>=" shifts the bits of the value on the left-hand side to the right by the number of positions specified by the value on the right-hand side. It then assigns the result back to the left-hand side variable.

x >>= 2; // Binary: 101 (Shifted right by 2 positions) // After right shift assignment: x = 5 (Binary: 101)

Conclusion The assignment operator in C, denoted by the equals sign (=), is used to assign a value to a variable. It is a fundamental operation that allows programmers to store data in variables for further use in their code. In addition to the simple assignment operator, C provides compound assignment operators that combine arithmetic or bitwise operations with assignment, allowing for concise and efficient code.

FAQs related to Assignment Operator in C

Q1. Can I assign a value of one data type to a variable of another data type? In most cases, assigning a value of one data type to a variable of another data type will result in a warning or error from the compiler. It is generally recommended to assign values of compatible data types to variables.

Q2. What is the difference between the assignment operator (=) and the comparison operator (==)? The assignment operator (=) is used to assign a value to a variable, while the comparison operator (==) is used to check if two values are equal. It is important not to confuse these two operators.

Q3. Can I use multiple assignment operators in a single statement? No, it is not possible to use multiple assignment operators in a single statement. Each assignment operator should be used separately for assigning values to different variables.

Q4. Are there any limitations on the right-hand side value of the assignment operator? The right-hand side value of the assignment operator should be compatible with the data type of the left-hand side variable. If the data types are not compatible, it may lead to unexpected behavior or compiler errors.

Q5. Can I assign the result of an expression to a variable using the assignment operator? Yes, it is possible to assign the result of an expression to a variable using the assignment operator. For example, x = y + z; assigns the sum of y and z to the variable x.

Q6. What happens if I assign a value to an uninitialized variable? Assigning a value to an uninitialized variable will initialize it with the assigned value. However, it is considered good practice to explicitly initialize variables before using them to avoid potential bugs or unintended behavior.

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An operator is a symbol that operates on a value or a variable. For example: + is an operator to perform addition.

C has a wide range of operators to perform various operations.

C Arithmetic Operators

An arithmetic operator performs mathematical operations such as addition, subtraction, multiplication, division etc on numerical values (constants and variables).

Operator	Meaning of Operator
+	addition or unary plus
-	subtraction or unary minus
*	multiplication
/	division
%	remainder after division (modulo division)

Example 1: Arithmetic Operators

The operators + , - and * computes addition, subtraction, and multiplication respectively as you might have expected.

In normal calculation, 9/4 = 2.25 . However, the output is 2 in the program.

It is because both the variables a and b are integers. Hence, the output is also an integer. The compiler neglects the term after the decimal point and shows answer 2 instead of 2.25 .

The modulo operator % computes the remainder. When a=9 is divided by b=4 , the remainder is 1 . The % operator can only be used with integers.

Suppose a = 5.0 , b = 2.0 , c = 5 and d = 2 . Then in C programming,

C Increment and Decrement Operators

C programming has two operators increment ++ and decrement -- to change the value of an operand (constant or variable) by 1.

Increment ++ increases the value by 1 whereas decrement -- decreases the value by 1. These two operators are unary operators, meaning they only operate on a single operand.

Example 2: Increment and Decrement Operators

Here, the operators ++ and -- are used as prefixes. These two operators can also be used as postfixes like a++ and a-- . Visit this page to learn more about how increment and decrement operators work when used as postfix .

C Assignment Operators

An assignment operator is used for assigning a value to a variable. The most common assignment operator is =

Operator	Example	Same as
=	a = b	a = b
+=	a += b	a = a+b
-=	a -= b	a = a-b
*=	a *= b	a = a*b
/=	a /= b	a = a/b
%=	a %= b	a = a%b

Example 3: Assignment Operators

C relational operators.

A relational operator checks the relationship between two operands. If the relation is true, it returns 1; if the relation is false, it returns value 0.

Relational operators are used in decision making and loops .

Operator	Meaning of Operator	Example
==	Equal to	is evaluated to 0
>	Greater than	is evaluated to 1
<	Less than	is evaluated to 0
!=	Not equal to	is evaluated to 1
>=	Greater than or equal to	is evaluated to 1
<=	Less than or equal to	is evaluated to 0

Example 4: Relational Operators

C logical operators.

An expression containing logical operator returns either 0 or 1 depending upon whether expression results true or false. Logical operators are commonly used in decision making in C programming .

Operator	Meaning	Example
&&	Logical AND. True only if all operands are true	If c = 5 and d = 2 then, expression equals to 0.
\|\|	Logical OR. True only if either one operand is true	If c = 5 and d = 2 then, expression equals to 1.
!	Logical NOT. True only if the operand is 0	If c = 5 then, expression equals to 0.

Example 5: Logical Operators

Explanation of logical operator program

(a == b) && (c > 5) evaluates to 1 because both operands (a == b) and (c > b) is 1 (true).
(a == b) && (c < b) evaluates to 0 because operand (c < b) is 0 (false).
(a == b) || (c < b) evaluates to 1 because (a = b) is 1 (true).
(a != b) || (c < b) evaluates to 0 because both operand (a != b) and (c < b) are 0 (false).
!(a != b) evaluates to 1 because operand (a != b) is 0 (false). Hence, !(a != b) is 1 (true).
!(a == b) evaluates to 0 because (a == b) is 1 (true). Hence, !(a == b) is 0 (false).

During computation, mathematical operations like: addition, subtraction, multiplication, division, etc are converted to bit-level which makes processing faster and saves power.

Bitwise operators are used in C programming to perform bit-level operations.

Operators	Meaning of operators
&	Bitwise AND
\|	Bitwise OR
^	Bitwise exclusive OR
~	Bitwise complement
<<	Shift left
>>	Shift right

Visit bitwise operator in C to learn more.

Other Operators

Comma operator.

Comma operators are used to link related expressions together. For example:

The sizeof operator

The sizeof is a unary operator that returns the size of data (constants, variables, array, structure, etc).

Example 6: sizeof Operator

Other operators such as ternary operator ?: , reference operator & , dereference operator * and member selection operator -> will be discussed in later tutorials.

Arithmetic Operators
Increment and Decrement Operators
Assignment Operators
Relational Operators
Logical Operators
sizeof Operator

Video: Arithmetic Operators in C

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Operators are used to perform operations on variables and values.

In the example below, we use the + operator to add together two values:

Although the + operator is often used to add together two values, like in the example above, it can also be used to add together a variable and a value, or a variable and another variable:

C divides the operators into the following groups:

Arithmetic operators
Assignment operators
Comparison operators
Logical operators
Bitwise operators

Arithmetic Operators

Arithmetic operators are used to perform common mathematical operations.

Operator	Name	Description	Example
+	Addition	Adds together two values	x + y
-	Subtraction	Subtracts one value from another	x - y
*	Multiplication	Multiplies two values	x * y
/	Division	Divides one value by another	x / y
%	Modulus	Returns the division remainder	x % y
++	Increment	Increases the value of a variable by 1	++x
--	Decrement	Decreases the value of a variable by 1	--x

Assignment Operators

Assignment operators are used to assign values to variables.

In the example below, we use the assignment operator ( = ) to assign the value 10 to a variable called x :

The addition assignment operator ( += ) adds a value to a variable:

A list of all assignment operators:

Operator	Example	Same As
=	x = 5	x = 5
+=	x += 3	x = x + 3
-=	x -= 3	x = x - 3
*=	x *= 3	x = x * 3
/=	x /= 3	x = x / 3
%=	x %= 3	x = x % 3
&=	x &= 3	x = x & 3
\|=	x \|= 3	x = x \| 3
^=	x ^= 3	x = x ^ 3
>>=	x >>= 3	x = x >> 3
<<=	x <<= 3	x = x << 3

Comparison Operators

Comparison operators are used to compare two values (or variables). This is important in programming, because it helps us to find answers and make decisions.

The return value of a comparison is either 1 or 0 , which means true ( 1 ) or false ( 0 ). These values are known as Boolean values , and you will learn more about them in the Booleans and If..Else chapter.

Comparison operators are used to compare two values.

Note: The return value of a comparison is either true ( 1 ) or false ( 0 ).

In the following example, we use the greater than operator ( > ) to find out if 5 is greater than 3:

A list of all comparison operators:

Operator	Name	Example	Description
==	Equal to	x == y	Returns 1 if the values are equal
!=	Not equal	x != y	Returns 1 if the values are not equal
>	Greater than	x > y	Returns 1 if the first value is greater than the second value
<	Less than	x < y	Returns 1 if the first value is less than the second value
>=	Greater than or equal to	x >= y	Returns 1 if the first value is greater than, or equal to, the second value
<=	Less than or equal to	x <= y	Returns 1 if the first value is less than, or equal to, the second value

Logical Operators

You can also test for true or false values with logical operators.

Logical operators are used to determine the logic between variables or values, by combining multiple conditions:

Operator	Name	Example	Description
&&	AND	x < 5 && x < 10	Returns 1 if both statements are true
\|\|	OR	x < 5 \|\| x < 4	Returns 1 if one of the statements is true
!	NOT	!(x < 5 && x < 10)	Reverse the result, returns 0 if the result is 1

C Exercises

Test yourself with exercises.

Fill in the blanks to multiply 10 with 5 , and print the result:

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There are different kinds of the operators, such as arithmetic, relational, bitwise, assignment, etc., in the C programming language. The assignment operator is used to assign the value, variable and function to another variable. Let's discuss the various types of the assignment operators such as =, +=, -=, /=, *= and %=.

It is the operator used to assign the right side operand or variable to the left side variable.

Let's create a program to use the simple assignment operator in C.

The operator is used to add the left side operand to the left operand and then assign results to the left operand.

Let's create a program to use the Plus and assign operator in C.

The operator is used to subtract the left operand with the right operand and then assigns the result to the left operand.

Let's create a program to use the Subtract and Assign (-=) operator in C.

The operator is used to multiply the left operand with the right operand and then assign result to the left operand.

Let's create a program to use the multiply and assign operator (*=) in C.

An operator is used between the left and right operands, which divides the first number by the second number to return the result in the left operand.

Let's create a program to use the divide and assign operator (/=) in C.

An operator used between the left operand and the right operand divides the first number (n1) by the second number (n2) and returns the remainder in the left operand.

Let's create a program to use the divide and assign operator (%=) in C.

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Assignment operators

8 contributors

expression assignment-operator expression

assignment-operator : one of = *= /= %= += -= <<= >>= &= ^= |=

Assignment operators store a value in the object specified by the left operand. There are two kinds of assignment operations:

simple assignment , in which the value of the second operand is stored in the object specified by the first operand.

compound assignment , in which an arithmetic, shift, or bitwise operation is performed before storing the result.

All assignment operators in the following table except the = operator are compound assignment operators.

Assignment operators table

Operator	Meaning
	Store the value of the second operand in the object specified by the first operand (simple assignment).
	Multiply the value of the first operand by the value of the second operand; store the result in the object specified by the first operand.
	Divide the value of the first operand by the value of the second operand; store the result in the object specified by the first operand.
	Take modulus of the first operand specified by the value of the second operand; store the result in the object specified by the first operand.
	Add the value of the second operand to the value of the first operand; store the result in the object specified by the first operand.
	Subtract the value of the second operand from the value of the first operand; store the result in the object specified by the first operand.
	Shift the value of the first operand left the number of bits specified by the value of the second operand; store the result in the object specified by the first operand.
	Shift the value of the first operand right the number of bits specified by the value of the second operand; store the result in the object specified by the first operand.
	Obtain the bitwise AND of the first and second operands; store the result in the object specified by the first operand.
	Obtain the bitwise exclusive OR of the first and second operands; store the result in the object specified by the first operand.
	Obtain the bitwise inclusive OR of the first and second operands; store the result in the object specified by the first operand.

Operator keywords

Three of the compound assignment operators have keyword equivalents. They are:

Operator	Equivalent

C++ specifies these operator keywords as alternative spellings for the compound assignment operators. In C, the alternative spellings are provided as macros in the <iso646.h> header. In C++, the alternative spellings are keywords; use of <iso646.h> or the C++ equivalent <ciso646> is deprecated. In Microsoft C++, the /permissive- or /Za compiler option is required to enable the alternative spelling.

Simple assignment

The simple assignment operator ( = ) causes the value of the second operand to be stored in the object specified by the first operand. If both objects are of arithmetic types, the right operand is converted to the type of the left, before storing the value.

Objects of const and volatile types can be assigned to l-values of types that are only volatile , or that aren't const or volatile .

Assignment to objects of class type ( struct , union , and class types) is performed by a function named operator= . The default behavior of this operator function is to perform a member-wise copy assignment of the object's non-static data members and direct base classes; however, this behavior can be modified using overloaded operators. For more information, see Operator overloading . Class types can also have copy assignment and move assignment operators. For more information, see Copy constructors and copy assignment operators and Move constructors and move assignment operators .

An object of any unambiguously derived class from a given base class can be assigned to an object of the base class. The reverse isn't true because there's an implicit conversion from derived class to base class, but not from base class to derived class. For example:

Assignments to reference types behave as if the assignment were being made to the object to which the reference points.

For class-type objects, assignment is different from initialization. To illustrate how different assignment and initialization can be, consider the code

The preceding code shows an initializer; it calls the constructor for UserType2 that takes an argument of type UserType1 . Given the code

the assignment statement

can have one of the following effects:

Call the function operator= for UserType2 , provided operator= is provided with a UserType1 argument.

Call the explicit conversion function UserType1::operator UserType2 , if such a function exists.

Call a constructor UserType2::UserType2 , provided such a constructor exists, that takes a UserType1 argument and copies the result.

Compound assignment

The compound assignment operators are shown in the Assignment operators table . These operators have the form e1 op = e2 , where e1 is a non- const modifiable l-value and e2 is:

an arithmetic type

a pointer, if op is + or -

a type for which there exists a matching operator *op*= overload for the type of e1

The built-in e1 op = e2 form behaves as e1 = e1 op e2 , but e1 is evaluated only once.

Compound assignment to an enumerated type generates an error message. If the left operand is of a pointer type, the right operand must be of a pointer type, or it must be a constant expression that evaluates to 0. When the left operand is of an integral type, the right operand must not be of a pointer type.

Result of built-in assignment operators

The built-in assignment operators return the value of the object specified by the left operand after the assignment (and the arithmetic/logical operation in the case of compound assignment operators). The resultant type is the type of the left operand. The result of an assignment expression is always an l-value. These operators have right-to-left associativity. The left operand must be a modifiable l-value.

In ANSI C, the result of an assignment expression isn't an l-value. That means the legal C++ expression (a += b) += c isn't allowed in C.

Expressions with binary operators C++ built-in operators, precedence, and associativity C assignment operators

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C operator precedence.















(C11)









Miscellaneous

General




(C11)







(C99)

The following table lists the precedence and associativity of C operators. Operators are listed top to bottom, in descending precedence.

Precedence	Operator	Description	Associativity
1		Suffix/postfix increment and decrement	Left-to-right
		Function call
		Array subscripting
		Structure and union member access
		Structure and union member access through pointer
	){ }	Compound literal(C99)
2		Prefix increment and decrement	Right-to-left
		Unary plus and minus
		Logical NOT and bitwise NOT
	)	Cast
		Indirection (dereference)
		Address-of
		Size-of
		Alignment requirement(C11)
3		Multiplication, division, and remainder	Left-to-right
4		Addition and subtraction
5		Bitwise left shift and right shift
6		For relational operators < and ≤ respectively
6		For relational operators > and ≥ respectively
7		For relational = and ≠ respectively
8		Bitwise AND
9		Bitwise XOR (exclusive or)
10		Bitwise OR (inclusive or)
11		Logical AND
12		Logical OR
13		Ternary conditional	Right-to-left
14		Simple assignment
		Assignment by sum and difference
		Assignment by product, quotient, and remainder
		Assignment by bitwise left shift and right shift
		Assignment by bitwise AND, XOR, and OR
15		Comma	Left-to-right

↑ The operand of prefix ++ and -- can't be a type cast. This rule grammatically forbids some expressions that would be semantically invalid anyway. Some compilers ignore this rule and detect the invalidity semantically.
↑ The operand of sizeof can't be a type cast: the expression sizeof ( int ) * p is unambiguously interpreted as ( sizeof ( int ) ) * p , but not sizeof ( ( int ) * p ) .
↑ The expression in the middle of the conditional operator (between ? and : ) is parsed as if parenthesized: its precedence relative to ?: is ignored.
↑ Assignment operators' left operands must be unary (level-2 non-cast) expressions. This rule grammatically forbids some expressions that would be semantically invalid anyway. Many compilers ignore this rule and detect the invalidity semantically. For example, e = a < d ? a ++ : a = d is an expression that cannot be parsed because of this rule. However, many compilers ignore this rule and parse it as e = ( ( ( a < d ) ? ( a ++ ) : a ) = d ) , and then give an error because it is semantically invalid.

When parsing an expression, an operator which is listed on some row will be bound tighter (as if by parentheses) to its arguments than any operator that is listed on a row further below it. For example, the expression * p ++ is parsed as * ( p ++ ) , and not as ( * p ) ++ .

Operators that are in the same cell (there may be several rows of operators listed in a cell) are evaluated with the same precedence, in the given direction. For example, the expression a = b = c is parsed as a = ( b = c ) , and not as ( a = b ) = c because of right-to-left associativity.

[ edit ] Notes

Precedence and associativity are independent from order of evaluation .

The standard itself doesn't specify precedence levels. They are derived from the grammar.

In C++, the conditional operator has the same precedence as assignment operators, and prefix ++ and -- and assignment operators don't have the restrictions about their operands.

Associativity specification is redundant for unary operators and is only shown for completeness: unary prefix operators always associate right-to-left ( sizeof ++* p is sizeof ( ++ ( * p ) ) ) and unary postfix operators always associate left-to-right ( a [ 1 ] [ 2 ] ++ is ( ( a [ 1 ] ) [ 2 ] ) ++ ). Note that the associativity is meaningful for member access operators, even though they are grouped with unary postfix operators: a. b ++ is parsed ( a. b ) ++ and not a. ( b ++ ) .

[ edit ] References

C17 standard (ISO/IEC 9899:2018):
A.2.1 Expressions
C11 standard (ISO/IEC 9899:2011):
C99 standard (ISO/IEC 9899:1999):
C89/C90 standard (ISO/IEC 9899:1990):
A.1.2.1 Expressions

[ edit ] See also

Order of evaluation of operator arguments at run time.

Common operators

a = b a += b a -= b a *= b a /= b a %= b a &= b a \|= b a ^= b a <<= b a >>= b	++a --a a++ a--	+a -a a + b a - b a * b a / b a % b ~a a & b a \| b a ^ b a << b a >> b	!a a && b a \|\| b	a == b a != b a < b a > b a <= b a >= b	a[b] *a &a a->b a.b	a(...) a, b (type) a a ? b : c sizeof _Alignof (since C11)

for C++ operator precedence

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21.12 — Overloading the assignment operator

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Assignment Operators In C++

In C++, the assignment operator forms the backbone of many algorithms and computational processes by performing a simple operation like assigning a value to a variable. It is denoted by equal sign ( = ) and provides one of the most basic operations in any programming language that is used to assign some value to the variables in C++ or in other words, it is used to store some kind of information.

The right-hand side value will be assigned to the variable on the left-hand side. The variable and the value should be of the same data type.

The value can be a literal or another variable of the same data type.

Compound Assignment Operators

In C++, the assignment operator can be combined into a single operator with some other operators to perform a combination of two operations in one single statement. These operators are called Compound Assignment Operators. There are 10 compound assignment operators in C++:

Addition Assignment Operator ( += )
Subtraction Assignment Operator ( -= )
Multiplication Assignment Operator ( *= )
Division Assignment Operator ( /= )
Modulus Assignment Operator ( %= )
Bitwise AND Assignment Operator ( &= )
Bitwise OR Assignment Operator ( |= )
Bitwise XOR Assignment Operator ( ^= )
Left Shift Assignment Operator ( <<= )
Right Shift Assignment Operator ( >>= )

Lets see each of them in detail.

1. Addition Assignment Operator (+=)

In C++, the addition assignment operator (+=) combines the addition operation with the variable assignment allowing you to increment the value of variable by a specified expression in a concise and efficient way.

This above expression is equivalent to the expression:

2. Subtraction Assignment Operator (-=)

The subtraction assignment operator (-=) in C++ enables you to update the value of the variable by subtracting another value from it. This operator is especially useful when you need to perform subtraction and store the result back in the same variable.

3. Multiplication Assignment Operator (*=)

In C++, the multiplication assignment operator (*=) is used to update the value of the variable by multiplying it with another value.

4. Division Assignment Operator (/=)

The division assignment operator divides the variable on the left by the value on the right and assigns the result to the variable on the left.

5. Modulus Assignment Operator (%=)

The modulus assignment operator calculates the remainder when the variable on the left is divided by the value or variable on the right and assigns the result to the variable on the left.

6. Bitwise AND Assignment Operator (&=)

This operator performs a bitwise AND between the variable on the left and the value on the right and assigns the result to the variable on the left.

7. Bitwise OR Assignment Operator (|=)

The bitwise OR assignment operator performs a bitwise OR between the variable on the left and the value or variable on the right and assigns the result to the variable on the left.

8. Bitwise XOR Assignment Operator (^=)

The bitwise XOR assignment operator performs a bitwise XOR between the variable on the left and the value or variable on the right and assigns the result to the variable on the left.

9. Left Shift Assignment Operator (<<=)

The left shift assignment operator shifts the bits of the variable on the left to left by the number of positions specified on the right and assigns the result to the variable on the left.

10. Right Shift Assignment Operator (>>=)

The right shift assignment operator shifts the bits of the variable on the left to the right by a number of positions specified on the right and assigns the result to the variable on the left.

Also, it is important to note that all of the above operators can be overloaded for custom operations with user-defined data types to perform the operations we want.

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Overloading assignment operator in a class template that can cast to another template type

The commented assignment operator overloading is my attempt to do what I want, I thought it might provide a better description than the one above the snippet.

I want to be able to do the following:

Where a then would be casted to an int and given the value of b , but still be an instance of class Number .

Is it possible? Can you help me out here?

Thanks in advance.

What's wrong with the default assignment operator, combined with the implicit conversion provided by the constructor? That will do exactly what your operators are trying to do, without having to write any code. – Mike Seymour Commented Nov 29, 2011 at 4:50
It's been a while since I did C++ but you can also override the cast/conversion operator. – Steve Wellens Commented Nov 29, 2011 at 4:52

3 Answers 3

You should do this:

That is, use T2 in the parameter type, not in the return type!

I would rather use different letter for template parameter:

I think, it is better to use explicit cast, if you want to use class type as template argument and whose constructor has been declared explicit :

By the way, the other operator= should be implemented as:

1 Yep, thanks a lot. @SethCarnegie asked what happened when I uncommented the code, at the same time I uncommented it I realized the way I was checking the result was with printf() using %d instead of %f of the float. Silly. Thanks to both of you. – mkroman Commented Nov 29, 2011 at 4:53

You have some of the T s in the wrong place. It should be

This will let you do

and it will print 6 , a behaviour similar to that of the int and float types you are imitating.

In case you want more of a built-in feel, the value() and setValue() can be replaced with assignment and cast:

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C++ Operators

COMMENTS

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c
An assignment expression has the value of the left operand after the assignment. It's to allow things like this: a = b = c; (although there's some debate as to whether code like that is a good thing or not.) Incidentally, this behaviour is replicated in Java (and I would bet that it's the same in C# too). edited Feb 20, 2017 at 8:59.
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c++
Since user defined classes and structs can be complex sometimes you need to provide a custom assignment operator to do things like deep copies of pointer members. MyObject a; MyObject b; b = a; // calls assignment operator b.operator=(a); Note you can't overload operators in C and Java probably does it differently.
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The assignment operator can't be overloaded as a stand-alone (non-member) function. If you have control of the class, and can modify it, you can make a conversion operator: operator double() const { return todouble(); } It must still be a member function though. double is not a class and does not have members.
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In C++, the assignment operator forms the backbone of many algorithms and computational processes by performing a simple operation like assigning a value to a variable. It is denoted by equal sign ( = ) and provides one of the most basic operations in any programming language that is used to assign some value to the variables in C++ or in other ...
c++
The commented assignment operator overloading is my attempt to do what I want, I thought it might provide a better description than the one above the snippet.