Return values and their types

In C, a return value is the value that a function sends back to the part of the program that called it after completing its task. The return type specifies the type of data that a function returns. If a function does not return a value, the return type is void.

Types of Return Values:

Syntax for Returning a Value:

return expression;

#include <stdio.h>

// Function declaration
int add(int, int);

int main() {
  int result = add(5, 10);       // Function call
  printf("Sum: %d\n", result);     // Output: Sum: 15
  return 0;
}

// Function definition
int add(int a, int b) {
  return a + b; // Returning the sum of a and b
}

• Return type: int because the function add() returns an integer.
• Return value: The sum of the two integers a and b.

2. Floating-Point Return Type (float)

#include <stdio.h>

float divide(float, float);

int main() {
  float result = divide(9.0, 3.0); 
  printf("Quotient: %.2f\n", result); 
  return 0;
}

float divide(float a, float b) {
  return a / b; 
}

• Return type: float because the function returns a floating-point number.
• Return value: The division result of a and b.

3. Character Return Type (char)

#include <stdio.h>

char getGrade(int);

int main() {
  int score = 85;
  char grade = getGrade(score); 
  printf("Grade: %c\n", grade); 
  return 0;
}

char getGrade(int marks) {
  if (marks >= 90) {
    return 'A';
  } else if (marks >= 80) {
    return 'B';
  } else if (marks >= 70) {
    return 'C';
  } else {
    return 'F';
  }
}

4. Void Return Type (void)

A function with a void return type does not return a value. It performs some operation but doesnÖt send anything back to the calling function.

#include <stdio.h>

void printHello(void);

int main() {
  printHello();
  return 0;
}

void printHello(void) {
  printf("Hello, World!\n"); // No return statement
}

5. Pointer Return Type

A function can return a pointer to a particular data type.

#include <stdio.h>

int* getMax(int*, int*);

int main() {
  int a = 10, b = 20;
  int* max = getMax(&a, &b); 
  printf("Max: %d\n", *max); 
  return 0;
}

int* getMax(int* x, int* y) {
  if (*x > *y) {
    return x; 
  } else {
    return y;
  }
}

Multiple Return Statements:

A function can have multiple return statements, typically in cases like conditional logic (if-else or switch-case), but it will only return once when the first return statement is encountered.

int checkEvenOdd(int num) {
  if (num % 2 == 0) {
    return 1; 
  } else {
    return 0; 
  }
}

Functions with No Return Value (void):

• If a function does not return a value, its return type is void, and there is no need for a return statement unless you just want to exit the function early.

void printMessage(void) {
  printf("This function returns nothing.\n");
  return; 
}

int wrongFunction() {
  return 3.14; 
}

In this case, the return value should be explicitly cast to an integer:

int correctFunction() {
  return (int)3.14; 
}

So basically, return serves two purpose

• On executing the return statement, it immediately transfers the control back to the calling function.
• It returns the value present in the parentheses after return, to the calling function.