C function argument and return values

30 May, 2022
Prerequisite: Functions in C/C++ A function in C can be called either with arguments or without arguments. These functions may or may not return values to the calling functions. All C functions can be called either with arguments or without arguments in a C program. Also, they may or may not return any values. Hence the function prototype of a function in C is as below: |
Function with no argument and no return value: When a function has no arguments, it does not receive any data from the calling function. Similarly, when it does not return a value, the calling function does not receive any data from the called function. Syntax :
Function with no argument and no return value: When a function has no arguments, it does not receive any data from the calling function. Similarly, when it does not return a value, the calling function does not receive any data from the called function. Syntax :
Function declaration : void function();
Function call : function();
Function definition :
                      void function()
                      {
                        statements;
                      }
C
// C code for function with no// arguments and no return value #include <stdio.h>void value(void);void main(){    value();}void value(void){    float year = 1, period = 5, amount = 5000, inrate = 0.12;    float sum;    sum = amount;    while (year <= period) {        sum = sum * (1 + inrate);        year = year + 1;    }    printf(" The total amount is %f:", sum);}
 The total amount is 8811.708984:
Function with arguments but no return value: When a function has arguments, it receives any data from the calling function but it returns no values. Syntax :
Function with arguments but no return value: When a function has arguments, it receives any data from the calling function but it returns no values. Syntax :
Function declaration : void function ( int );
Function call : function( x );
Function definition:
             void function( int x )
             {
               statements;
             }
C
// C code for function// with argument but no return value#include <stdio.h> void function(int, int[], char[]);int main(){    int a = 20;    int ar[5] = { 10, 20, 30, 40, 50 };    char str[30] = "geeksforgeeks";    function(a, &ar[0], &str[0]);    return 0;} void function(int a, int* ar, char* str){    int i;    printf("value of a is %d\n\n", a);    for (i = 0; i < 5; i++) {        printf("value of ar[%d] is %d\n", i, ar[i]);    }    printf("\nvalue of str is %s\n", str);}
value of a is 20

value of ar[0] is 10
value of ar[1] is 20
value of ar[2] is 30
value of ar[3] is 40
value of ar[4] is 50

value of str is geeksforgeeks

Function with no arguments but returns a value: There could be occasions where we may need to design functions that may not take any arguments but returns a value to the calling function. An example of this is getchar function it has no parameters but it returns an integer and integer type data that represents a character. Syntax :
Function with no arguments but returns a value: There could be occasions where we may need to design functions that may not take any arguments but returns a value to the calling function. An example of this is getchar function it has no parameters but it returns an integer and integer type data that represents a character. Syntax :
Function declaration : int function();
Function call : function();
Function definition :
                 int function()
                 {
                     statements;
                      return x;
                  }
    
C
// C code for function with no arguments// but have return value#include <math.h>#include <stdio.h> int sum();int main(){    int num;    num = sum();    printf("\nSum of two given values = %d", num);    return 0;} int sum(){    int a = 50, b = 80, sum;    sum = sqrt(a) + sqrt(b);    return sum;}
Sum of two given values = 16
Function with arguments and return value Syntax :
Function with arguments and return value Syntax :
Function declaration : int function ( int );
Function call : function( x );
Function definition:
             int function( int x )
             {
               statements;
               return x;
             }
C
// C code for function with arguments// and with return value #include <stdio.h>#include <string.h>int function(int, int[]); int main(){    int i, a = 20;    int arr[5] = { 10, 20, 30, 40, 50 };    a = function(a, &arr[0]);    printf("value of a is %d\n", a);    for (i = 0; i < 5; i++) {        printf("value of arr[%d] is %d\n", i, arr[i]);    }    return 0;} int function(int a, int* arr){    int i;    a = a + 20;    arr[0] = arr[0] + 50;    arr[1] = arr[1] + 50;    arr[2] = arr[2] + 50;    arr[3] = arr[3] + 50;    arr[4] = arr[4] + 50;    return a;}
value of a is 40
value of arr[0] is 60
value of arr[1] is 70
value of arr[2] is 80
value of arr[3] is 90
value of arr[4] is 100

touristeye
harendrakumar123
C-Functions
CBSE - Class 11
school-programming
C Language
C++
CPP
Writing code in comment?
Please use ide.geeksforgeeks.org,
generate link and share the link here.