Check out example codes for "how to write function in c". It will help you in understanding the concepts better.

Code Example 1

#include <stdio.h>
#include <stdlib.h>
void functionName()
{
	// some code here
}
int main()
{
    functionName();
}

Code Example 2

#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();
}

Code Example 3

#include <stdio.h>

void function(){
  printf("I am a function!");
}

int main(void) {
  
  function();
}

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