Assignment Operators in C

The Assignment operators in C are useful to assign values to declared variables. The equals (=) operator is the most commonly used assignment operator. For example: int i = 10; Here, i is the variable, and 10 is the value assigned to the variable i.

Assignment operators in C can also be combined with arithmetic and bitwise operators to perform arithmetic and bitwise operations.

List of all assignment operators in C

The table below displays all the assignment operators in this programming language with a simple example.

Operator	Assignment Operator Name	Example	Explanation
=	Simple Assignment	x = 25	Value 25 is assigned to x
+=	Addition Assignment	x += 25	Same as x = x + 25
-=	Subtraction Assignment	x -= 25	Same as x = x – 25
*=	Multiplication Assignment	x *= 25	Same as x = x * 25
/=	Division Assignment	x /= 25	Same as x = x / 25
%=	Modulus Assignment	x%= 25	Same as x = x % 25
&=	Bitwise AND Assignment	x &= 25	x = x & 25
\|=	Bitwise OR Assignment	x \|= 25	x = x \| 25
^=	Bitwise XOR Assignment	x ^= 25	x = x ^ 25
>>=	Bitwise Right Shift Assignment	x >>= 25	x = x >> 25
<<=	Bitwise Left Shift Assignment	x <<= 25	x = x << 25

Simple Assignment Operator (=)

The = operator is one of the most common assignment operators in C programming language. It is used to assign values to the variables.

a = 10 means assigning the value 10 to the variable ‘a’.

#include <stdio.h>
int main() 
{
    int amount;

    amount = 10000;
    printf("Amount = %d\n", amount);
    return 0;
}

Computed Assignment Operators in C

In addition to the common = operator, we can combine the = operator with arithmetic and bitwise operators to form an augmented or computed assignment operator.

Combining the = symbol with arithmetic operators (+, -, *, /, and %) and Bitwise operators (&, |, ^, <<, and >>) makes the code shorter and more efficient. For example, a += b instead of a = a + b. This section covers all the computed assignment operators in C programming language, along with examples.

Addition Assignment (+=)

The += operator performs the addition and stores the result back in the left variable.

a += b is equivalent to

a = a + b.

It means += performs the addition of a and b and stores the result back to the variable ‘a’.

#include <stdio.h>
int main() 
{
    int amount = 10000;
    int bonus = 2500;

    amount += bonus;
    printf("Total = %d", amount);
    return 0;
}

Total = 12500

Subtraction Assignment (-=)

The -= assignment operators in C subtracts the right operand from the left variable and stores the result in the left variable.

a -= b is equivalent to

a = a – b.

It means -= subtract b from a and stores the result back to the variable ‘a’.

#include <stdio.h>
int main() 
{
    int amount = 50000;
    int withdraw = 10000;

    amount -= withdraw;
    printf("Balance Amount = %d", amount);
    return 0;
}

Multiplication Assignment Operators in C (+=)

The *= operator performs the multiplication (left operand multiplied by right value) and stores the result back in the left variable.

a *= b is equivalent to

a = a * b.

It means *= multiplies a by b and stores the result back to the variable ‘a’. In the example below, amount *= interest means amount = 100000 * 1.75.

#include <stdio.h>
int main() 
{
    float amount = 100000;
    float interest = 1.75;

    amount *= interest;
    printf("Total Amount = %.2f", amount);
    return 0;
}

Total Amount = 175000.00

Division Assignment (/=)

The /= operator performs the division (dividing the left operand by the right value) and stores the result back in the left variable.

a /= b is equivalent to

a = a / b.

It means /= performs division (dividing a by b) and stores the result back to the variable ‘a’. In the example below, marks /= subjects means marks = 560 / 6 = 93.33.

#include <stdio.h>
int main() 
{
    float marks = 560;
    int subjects = 6;

    marks /= subjects;
    printf("Marks Percentage = %.2f", marks);
    return 0;
}

Marks Percentage = 93.33

Modulus Assignment (%=)

The /= assignment operators in C divides the left operand by the right operand and stores the remainder back in the left variable.

a %= b is equivalent to

a = a % b.

It means %= performs division (dividing a by b) and stores the remainder in the variable ‘a’. Here, 20 divided by 3 yields a remainder of 2 and a quotient of 6. (3 * 6 = 18, and 2 is the remainder).

#include <stdio.h>
int main()
{
    int a = 20;
    int b = 3;

    a %= b;
    printf("Remainder = %d", a);
    return 0;
}

Bitwise Assignment Operators in C

Bitwise AND Assignment (&=)

The &= operator performs the bitwise AND operation on two operands and stores the result in the first (left) variable.

a &= b is equivalent to

a = a & b.

In the example below, 12 = 1100 and 8 = 1000. There is only one place where 1 & 1 exists (True), so the result is 1000 = 8.

#include <stdio.h>
int main()
{
    int a = 12;
    int b = 8;

    a &= b;
    printf("Result = %d", a);
    return 0;
}

Bitwise OR Assignment (|=)

The |= operator performs the bitwise OR operation and stores the result in the first (left) variable.

a |= b is equivalent to

a = a | b.

In the example below, 1100 | 1000 returns 1100 = 12.

#include <stdio.h>
int main()
{
    int a = 12;
    int b = 8;

    a |= b;
    printf("Result = %d", a);
    return 0;
}

Bitwise XOR Assignment Operators in C (^=)

The ^= operator performs the bitwise XOR operation and stores the result in the first (left) variable.

a ^= b is equivalent to

a = a ^ b.

#include <stdio.h>

In the example below, 1100 | 1000 = 0100 = 4.

int main()
{
    int a = 12;
    int b = 8;

    a ^= b;
    printf("Result = %d", a);
    return 0;
}

Bitwise Left Shift Assignment (<<=)

The <<= assignment operators in C shifts the left operand bits to the left side by the positions mentioned in the right operand and stores the result in a left variable.

a <<= b is equivalent to

a = a << b.

In the example below, 00001100 << 2 = 00110000 = 48 (32 + 16).

#include <stdio.h>
int main()
{
    int a = 12;
    int b = 2;

    a <<= b;
    printf("Result = %d", a);
    return 0;
}

Bitwise Right Shift Assignment (>>=)

The >>= operator shifts the left operand bits to the right side by the positions mentioned in the right operand and stores the result in a left variable.

a >>= b is equivalent to

a = a >> b.

In the example below, 1100 >> 2 = 0011 = 3 (2 + 1).

#include <stdio.h>
int main()
{
    int a = 12;
    int b = 2;

    a >>= b;
    printf("Result = %d", a);
    return 0;
}

Example of 6 Assignment Operators in C

In this assignment operators Program, We are using two integer variables a, and Total, and their values are 7 and 21. Next, we are going to use these two variables to show you the working functionality of all the Assignment Operators in this Programming Language

/* Program for Assignment Operators */

#include <stdio.h>

int main()
{
 int a = 7;
 int Total = 21;

 printf(" Value of the Total = %d \n", Total += a );
 printf(" Value of the Total = %d \n", Total -= a );
 printf(" Value of the Total = %d \n", Total *= a );
 printf(" Value of the Total = %d \n", Total /= a );
 printf(" Value of the Total = %d \n", Total %= a );

 return 0;
}

The below printf statements will perform C Programming Assignment operations on a and Total and then the output of the result will be displayed. Let us see the C Programming Operator functionality in this C Program

printf(" Value of the Total = %d \n ", Total += a );

Total += a means
Total = Total + a = 21 + 7 = 28

printf(" Value of the Total = %d \n", Total -= a );

Next, Total -= a means
Total = Total – a = 28 – 7 = 21

 printf(" Value of the Total = %d \n", Total *= a );

Total *= a means
Total = Total * a = 21 * 7 = 147

 printf(" Value of the Total = %d \n", Total /= a );

Next, Total /= a means
Total = Total / a = 147 / 7 = 21.

printf(" Value of the Total = %d \n", Total %= a );

Total %= a means
Total = Total + a = 21 % 7 = 0 (Remainder of 21/7 is = 0).

Chaining Assignments in C

Chaining assignments is nothing but linking multiple assignment operators in C language together. For instance, a = b = c = 10.

Here, the evaluation happens from right to left. So, the above expression is equivalent to

c = 10;

b = c;

a = b;

In the example below, 10 is assigned to variable c, then it is assigned to b, and finally, 10 is assigned to a.

#include <stdio.h>

int main()
{
    int a, b, c;
    a = b = c = 10;

    printf("a = %d\n", a);
    printf("b = %d\n", b);
    printf("c = %d\n", c);
    return 0;
}

a = 10
b = 10
c = 10

Chaining with Computed assignment

In the following example, the evaluation starts from the right.

b *= 5 => b = 20 * 5 = 100.
a += b => a = 10 + 100 = 110.

#include <stdio.h>
int main()
{
    int a = 10, b = 20;

    a += b *= 5;
    printf("a = %d\n", a);
    printf("b = %d", b);
    return 0;
}

a = 110
b = 100

Using C Assignment Operators in Loops

We can use assignment operators in loops such as the for loop, a while loop, and a do while loop.

#include <stdio.h>
int main()
{
    int sum = 0;
    for (int i = 1; i <= 10; i++)
    {
        sum += i;
    }
    printf("Total = %d\n", sum);
    return 0;
}

Total = 55

What is the difference between = and == in C?

= operator: It assigns a value to the variable. For instance, a = 10.
== Operator: It is a comparison operator that compares one value against the other. For instance, if(a == 10) { //code}.