Basic Structure of C Code

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<math.h>

float myAvg(float num1, float num2); //func proto

int main()
{
    float a=3.1, b=3.5;
    printf("The avg is %f", myAvg(a,b) );
    return 0;
}

float myAvg(float num1, float num2)
{
    float answer;
    answer=(num1 + num2)/2;
    return answer;
}