C

c functions example

#include <stdio.h>
int addNumbers(int a, int b);         // function prototype

int main()
{
    int n1,n2,sum;

    printf("Enters two numbers: ");
    scanf("%d %d",&n1,&n2);

    sum = addNumbers(n1, n2);        // function call
    printf("sum = %d",sum);

    return 0;
}

int addNumbers(int a, int b)         // function definition   
{
    int result;
    result = a+b;
    return result;                  // return statement
}

c define function

//INCLUDING BUILT-IN LIBRARIES...
#include <stdio.h>
#include <stdlib.h>
//PRE-DEFINE CONSTANT VALUES...
#define MAXNUM -12    //defining an integer
#define PI 3.1415     //defining a float
#define END "

		Program has ended!!
"   //defining a string
//PRE-DEFINING CONSTANT OPERATIONS...
#define ADD(a, b, c) (a + b + c)    //Operation that will add its 3 parameters

int main(){
    //using other definitions to check if the current device is Windows or UNIX
    #ifdef _WIN32   
        printf("
Windows Operating System Detected
");
    #elif linux
        printf("
UNIX Operating System Detected
");
    #else
        printf("
Operating System could NOT be identified!
");
    #endif
    
    printf("
Using pre-defined values and operations: ");
    printf("
 • MAXNUM: %d",MAXNUM);       //using pre-defined integer
    printf("
 • PI: %f",PI);               //using pre-defined float
    printf("
 • ADD(): %.2f",ADD(2,5,99.5));   //using pre-defined function

    printf(END);    //using pre-defined string
    return 0;
}

how to write function in c

#include <stdio.h>

// Here is a function declaraction
// It is declared as "int", meaning it returns an integer
/*
	Here are the return types you can use:
    	char,
        double,
        float,
        int,
        void(meaning there is no return type)
*/
int MyAge() {
	return 25;
}

// MAIN FUNCTION
int main(void) {
	// CALLING THE FUNCTION WE MADE
    MyAge();
}

C Function definition

returnType functionName(type1 argument1, type2 argument2, ...)
{
    //body of the function
}

c functions

#include <stdio.h>
void functionName()
{
    ... .. ...
    ... .. ...
}

int main()
{
    ... .. ...
    ... .. ...

    functionName();
    
    ... .. ...
    ... .. ...
}

function declaration in C

return_type function_name( parameter list );

Explain What are functions in c.

A function is a self-contained block of statements that perform a 
coherent task of some kind. Every C program can be thought of as 
a collection of these functions