Program works under C++ but not under C

This program is able to compile and run succesfully under C++, but not C. The program gives a AccessViolation error message on the first line using NULL. Is there some type of headfile I'm missing? I thought iostream.h allowed me to use null.
I'm using Borland C++ builder ver 5 and 6.

Code:

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#include <stdio.h>
#include <conio.h>
#include <process.h>
#include <string.h>
#include <stdlib.h>
#include <iostream.h>

int main()
{
  char  starting_time[10], ending_time[10];
  int  starting_hour = 0, ending_hour = 0, starting_minute = 0,
        ending_minute = 0, hour, minute;

  printf("Enter the starting time: ");
  scanf("%c", &starting_time);
  printf("Enter the ending time: ");
  scanf("%c", &ending_time);

  starting_hour = atoi( strtok( starting_time, ":" ) );
  starting_minute = atoi( strtok( NULL, ":" ) );
  ending_hour = atoi( strtok( ending_time, ":" ) );
  ending_minute = atoi( strtok( NULL, ":" ) );

  hour = ending_hour - starting_hour;
  minute = ending_minute - starting_minute;

  if ( hour < 0 )
  {
      hour = hour + 24;
  }
  if ( minute < 0 )
  {
      minute = minute + 60;
      hour = hour - 1;
  }

  printf("Elapsed time is: %d : %d", hour, minute);

  getch();
  return 0;
}

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You're including headers that only exist in C++. Use the standard C functions (and incidentally, according to the current standard, that code doesn't actually compile under C++ - use namespaces)

Code:

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  printf("Enter the starting time: ");
  scanf("%c", &starting_time);
  printf("Enter the ending time: ");
  scanf("%c", &ending_time);

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What is the type of &starting_time ? What type does scanf() expect with the %c modifier?

edit: whoopsie cancel that. But let that be a lesson: saying
&array confuses people! Say &array[0] or just array if thats what you mean.

PHP Code:

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#include <iostream.h> 


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Not required..

"Array name is pointers in C"

First class of array in your school.

Iv'e removed the iostream.h but I have no idea what your'e trying to say with your second post. Being a little bit more specific would help.
And I forgot to mention, when it compiled under C++, it did have a few other header files like pragma hdrstop and such.

#pragma hdrstop is not a header file. A header file is a source code file that is added to your code by the preprocessor, when it encounters the directive "include" (preprocessor directives all start with '#'. #pragma hdrstop tells the preprocessor that you're done including header files. It's not really necessary, and not really common. I've never seen it outside of my Borland user manual. Not even in lists of preprocessor directives online. Another common directive you'll see is define, which is used for macros (#define MAX 10 would go through your source code before compilation and replace every occurence of MAX with 10, literally.

Your code is broken - the fact that it works in one inplementation and not another is just dumb luck.

> scanf("%c", &starting_time);
This does NOT append a \0 to whatever you type in
Besides, it reads only 1 char, not a string

> starting_hour = atoi( strtok( starting_time, ":" ) );
This assumes many times that the input does have a \0

I really think you should be replacing those scanf calls with fgets calls.

Quote:

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Originally Posted by Roaring_Tiger

"Array name is pointers in C"

First class of array in your school.

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No.

Code:

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#include <stdio.h>
 
 int main() {
  char test1[20];
  char *test2;
 
  printf("pointer:%i, array:%i\n", sizeof(test1), sizeof(test2));
  return 0;
 }

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