Header file 1

 

Header file 1

 

#include <stdio.h>double mean( double *y, int N ){    int    i;    double    s = 0.0;    for ( i = 0; i < N; i++ )        s = s + y[i];    s = s / (double) N;    return(s);}void main(){    double x[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };    printf( "mean = %lf\n", mean( x, 10 ) );}

----------------------------------------------

Save the extracted part to a_x.h:

double mean( double *y, int N ){    int    i;    double    s = 0.0;    for ( i = 0; i < N; i++ )        s = s + y[i];    s = s / (double) N;    return(s);}

Program changes:

#include <stdio.h>#include "a_x.h"void main(){    double x[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };    printf( "mean = %lf\n", mean( x, 10 ) );}

 

========================================================== =====
You can also select a random part, for example, extract (also called a_x.h ):

double mean( double *y, int N ){    int    i;    double    s = 0.0;    for ( i = 0; i < N; i++ )        s = s + y[i];    s = s / (double) N;    return(s);}void main(){

------------------------
Program changes:

    #include<stdio.h>     #include "a_x.h"    double x[10]={1,2,3,4,5,6,7,8,9,10};    printf("mean = %lf\n", mean(x,10));}

====================================
In terms of syntax and function, both methods can be used. But the first method is better-the program is readable and error-prone.

Generally, the header file contains the function prototype, global volume declaration, and function definition.