Return Statement in C

The return statement in C is used to terminate a function and transfer control back to the calling function. It can also return a value from the function to the caller.

• The return statement ends the execution of a function.
• It may return a value or no value depending on the function's return type.

Syntax:

return return_value;

Example:

int add()

{
return 10;
}

Explanation: The function returns the value 10 to the calling function.

Return Statement in Void Functions

A void function does not return any value. Therefore, using a return statement is optional.

• Void functions do not return any value.
• The return; statement can be used to exit the function early.

Syntax Without Return Statement:

void functionName()
{
// statements
}

#include <stdio.h>

void display()
{
    printf("Hello World");
}

Explanation: The function executes normally and automatically ends after the last statement.

Syntax With Return Statement:

void functionName()
{
return;
}

#include <stdio.h>

void checkNumber(int num)
{
    if(num < 0)
        return;

    printf("Positive Number");
}

Explanation: The function exits immediately when the number is negative.

Incorrect Use of Return in Void Function

A void function cannot return a value.

Incorrect Syntax:

void display()
{
return 10;
}

void display()
{
    return 10;
}

Explanation: This causes a compilation error because a void function cannot return a value.

Return Statement in Functions Returning a Value

Functions with a non-void return type must return a value of the specified type.

• A return value is mandatory in non-void functions.
• The returned value must match the function's return type.

Syntax:

return expression;

int square(int num)
{
    return num * num;
}

Explanation: The function calculates and returns the square of the number.

Multiple Return Statements in a Function

A function can contain multiple return statements, but only one of them is executed during a function call.

• Multiple return statements are allowed.
• Function execution stops after the first executed return statement.

Syntax:

if(condition)
return value1;
return value2;

int findSign(int num)
{
    if(num > 0)
        return 1;

    return -1;
}

Explanation: The function returns 1 for positive numbers and -1 otherwise.

Returning Only One Value

The return statement can directly return only one value from a function.

• Only one value can be returned directly.
• The returned value can be a variable, constant, or expression.

Syntax:

return value;

int getAge()
{
    return 25;
}

Explanation: The function returns a single integer value.

Common Mistakes

1. Missing Return Statement:

int getNumber()
{
}

Explanation: Non-void functions must return a value.

2. Returning Wrong Data Type:

int getValue()
{
return "Hello";
}

Explanation: A string cannot be returned from a function with return type int.

3. Returning a Value from a Void Function:

void show()
{
return 100;
}

Explanation: Void functions cannot return values.

return; Vs return value