Thread: forward declaration error

Code:

// code to solve elapsed time between two entered times

#include <stdio.h>


    struct time
    {
         int hr;
         int min;
         int sec;
    };


int elapsed_time (struct time1, struct time2)
{
    struct time time1, time2, diff;
    
    diff.hr = time2.hr - time1.hr;
    if (time2.hr < time1.hr)
       diff.hr = diff.hr + 12;
 
    diff.min = time2.min - time1.min;
    if (time2.min < time1.min)
       diff.min = diff.min + 60;
      
    diff.sec = time2.sec - time1.sec; 
    if (time2.sec < time1.sec)
       diff.sec = diff.sec + 60;
      
    return diff;
}
int main (void)
{
    int stopit;
     
    struct time diff, time1, time2;
    int elapsed_time (struct time1, struct time2);
    
    printf ("Enter a military time (i.e. 24 hour basis) in the format hh:mm:ss\n");
    scanf ("%i:%i:%i", &time1.hr, &time1.min, &time1.sec);
    
    printf ("Enter a second military time using the same format.\n");    
    scanf ("%i:%i:%i", &time2.hr, &time2.min, &time2.sec);
    
    diff = elapsed_time (time1, time2);
    
    printf ("The elapsed time between the two times entered is %.2i:%.2i:%.2i\n", diff.hr, diff.min, diff.sec);
    scanf ("%d", &stopit);
return 0;
}

Code:

int elapsed_time (struct time1, struct time2)

You are not giving the full data type... It should be

Code:

int elapsed_time (struct time time1, struct time time2)

But even if you did that, your function will have the same variable names as your parameters. ex) line 16.
Either you want to change those names, or just remove them all together now since you are passing in those structures.

Line 37 does not need to be there since you have declared your function definitions above main.

Sorry Grumpy. I am a real beginner...taking my first course in C. I modified the program (see below) and now have a compiler error "declaration of 'time x' shadows a parameter. This has me stumped as well. Any help would be appreciated.

Code:

#include <stdio.h>


    struct time
    {
         int hr;
         int min;
         int sec;
    };


int elapsed_time (struct time x, struct time y)
{
    struct time x, y, diff;
    
    diff.hr = y.hr - x.hr;
    if (y.hr < x.hr)
       diff.hr = diff.hr + 12;
 
    diff.min = y.min - x.min;
    if (y.min < x.min)
       diff.min = diff.min + 60;
      
    diff.sec = y.sec - x.sec; 
    if (y.sec < x.sec)
       diff.sec = diff.sec + 60;
       
        printf ("The elapsed time between the two times entered is %.2i:%.2i:%.2i\n", diff.hr, diff.min, diff.sec);
}
int main (void)
{
    int stopit;
    
    
    struct time diff, time1, time2;
    int elapsed_time (struct time time1, struct time time2);
    
    printf ("Enter a military time (i.e. 24 hour basis) in the format hh:mm:ss\n");
    scanf ("%i:%i:%i", &time1.hr, &time1.min, &time1.sec);
    
    printf ("Enter a second military time using the same format.\n");    
    scanf ("%i:%i:%i", &time2.hr, &time2.min, &time2.sec);
    
    diff = elapsed_time (time1, time2);
    scanf ("%d", &stopit);
return 0;
}

Thank you for your help. The program compiles! It doesn't run, but it compiles. 1/2 way there.
beebee