Thread: Variable and functions declarations for header file

  1. #1
    Registered User
    Join Date
    May 2021
    Posts
    54

    Variable and functions declarations for header file

    I have written code following code

    Code:
    #include<stdio.h>
    
    void Wait ( unsigned int size )
    {
    	unsigned int  i;
    	
    	for ( i = 0; i < size; i++)
    	{
    		printf(" Loop = %d \n", i);
    	}
    }
    int main (void)
    {
    	 Wait ( 2);
    	return 0;
    }
    I want to create header file header.h"

    Code:
    #include<stdio.h>#include"header.h"
    
    
    int main (void)
    {
    	 Wait ( 2);
    	return 0;
    }
    What should be written in header.h?

  2. #2
    Registered User rstanley's Avatar
    Join Date
    Jun 2014
    Location
    New York, NY
    Posts
    869
    If Wait() and main() are in the same file as you show in the first example above, then you don't need a header file. Yes, you could create a header file even if they are in the same file, in preparation to add more functions and more .c files.

    If Wait() is in a separate file, then the prototype (declaration) for Wait() should be placed in the header file, and #include in both files.

    If you print out an unsigned int, then use "%u" to display.

    foo.c
    Code:
    #include<stdio.h>
    #include"header.h"
     
    int main (void)
    {
        Wait ( 2);
        return 0;
    }
    file1.c
    Code:
    #include<stdio.h>
    #include"header.h"
    
    void Wait ( unsigned int size )
    {
        unsigned int  i;
         
        for ( i = 0; i < size; i++)
        {
            printf(" Loop = %u \n", i);
        }
    }
    header.h
    Code:
    void Wait ( unsigned int size );
    Last edited by rstanley; 09-03-2021 at 08:13 AM.

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