C Programming Assignment Operators

What is an Assignment Operator in C?

Assignment Operators in C are used to assign values to the variables. They come under the category of binary operators as they require two operands to operate upon. The left side operand is called a variable and the right side operand is the value. The value on the right side of the "=" is assigned to the variable on the left side of "=". The value on the right side must be of the same data type as the variable on the left side. Hence, the associativity is from right to left.

In this C tutorial, we'll understand the types of C programming assignment operators with examples. To delve deeper you can enroll in our C Programming Course.

Before going in-depth about assignment operators you must know about operators in C. If you haven't visited the Operators in C tutorial, refer to Operators in C: Types of Operators.

Types of Assignment Operators in C

There are two types of assignment operators in C:

1. Simple Assignment Operator (=)

This assigns the value on the right-hand side (RHS) to the variable on the left-hand side (LHS). You can use a literal, another variable, or an expression in the assignment statement.

Example of Simple Assignment Operator

#include <stdio.h>
int main()
{
 int x;
 x = 30; 
 printf("The value of x is: %d\n", x);
 return 0;
}   

In this example, we have assigned the value 30 to the variable x using the assignment operator (=).

Output

30   

2. Compound Assignment Operators

In addition to the = operator, you can combine arithmetic and bitwise operators with the = symbol to form an augmented or compound assignment operator.

There are five combinations of arithmetic operators with the assignment operator, "=". Let's look at them one by one.

Example of Augmented Arithmetic and Assignment Operators

#include <stdio.h>

int main()
{
    int a = 20;
    printf("Value of a is %d\n", a);

    a += 20;
    printf("Value of a is %d\n", a);

    a -= 20;
    printf("Value of a is %d\n", a);

    a *= 20;
    printf("Value of a is %d\n", a);

    a /= 20;
    printf("Value of a is %d\n", a);

    return 0;
}    

Output

Value of a is 20
Value of a is 40
Value of a is 20
Value of a is 400
Value of a is 20   

There can be five combinations of bitwise operators with the assignment operator, "=". Let's look at them one by one.

Example of Augmented Bitwise and Assignment Operators

#include <stdio.h>

int main()
{
    int x=2, y=10;
   
    y <<= x;
    printf("Value of y is %d\n", y);

    y %= x;
      printf("Value of y is %d\n", y);

    y &= x;
        printf("Value of y is %d\n", y);

    y >>= x;
    printf("Value of y is %d\n", y);

    y |= x;
    printf("Value of y is %d\n", y);
    
    y ^= x;
    printf("Value of y is %d\n", y);
    
    return 0;
}

Output

Value of y is 40
Value of y is 0
Value of y is 0
Value of y is 0
Value of y is 2
Value of y is 0

Practice Problems on Assignment Operators in C

int x = 50;
x += 5;
x -= 3;

The correct answer is 52. x starts at 50, increases by 5 to 55, then decreases by 3 to 52.

2. After executing the following code, what is the value of the number variable?

int number = 73;
number >>= 1;
number <<= 2;

The correct answer is 144. After right-shifting 73 (binary 1001001) by one and then left-shifting the result by two, the value becomes 144 (binary 10010000).

Benefits of Using Assignment Operators

• Simplifies Code: For example, x += 1 is shorter and clearer than x = x + 1.
• Reduces Errors: They break complex expressions into simpler, more manageable parts thus reducing errors.
• Improves Readability: They make the code easier to read and understand by succinctly expressing common operations.
• Enhances Performance: They often operate in place, potentially reducing the need for additional memory or temporary variables.

Best Practices and Tips for Using the Assignment Operator

• Use Compound Assignment Operators for Clarity and Efficiency

  While performing arithmetic operations with the same variable, use compound assignment operators

  
  x += 5;  // Clear and concise compared to x = x + 5;
  

• Initialize Variables When Declaring

  
  int count = 0;  // Initialization
  

• Avoid Complex Expressions in Assignments

  
  a = (b + c) * (d - e);
  // Consider breaking it down:
  int temp = b + c;
  a = temp * (d - e);
  

• Avoid Multiple Assignments in a Single Statement

  
  // Instead of this
  a = b = c = 0;
  // Do this
  a = 0;
  b = 0;
  c = 0;
  

• Consistent Formatting

  
  int result = 0;
  result += 10;
  

• Use Parentheses for Clarity

  When mixing assignments with other operations, use parentheses to ensure the correct order of evaluation.

  Example

  
  x = (y + z) * w;  

Summary