Multiple exits

This is a discussion on Multiple exits within the C Programming forums, part of the General Programming Boards category; Developing Windows based C application. And following thing which annoys me a lot. Say I am calling few CreateFile functions ...

  1. #1
    Registered User
    Join Date
    Feb 2003
    Posts
    175

    Multiple exits

    Developing Windows based C application. And following thing which annoys me a lot.

    Say I am calling few CreateFile functions in my main function. Every time CreateFile function is invoked, it checks for result. And in each false statement I need to close and exit from application.

    e.g.
    Code:
    HANDLE h1,h2,h3,h4;
    
    h1 = CreateFile(..,..,..);
    if ( false )
    {
    	return;
    }
    
    h2 = CreateFile(..,..,..);
    if (false)
    {
    	CloseHandle(h1);
    	Exit;
    }
    
    h3 = CreateFile(..,..,..);
    if (false)
    {
    	CloseHandle(h1);
    	CloseHandle(h2);
    	Exit;
    }
    
    h4 = CreateFile(..,..,..);
    if (false)
    {
    	CloseHandle(h1);
    	CloseHandle(h2);
    	CloseHandle(h3);
    	Exit;
    }
    Firstly, do not like multiple exits in routine and on top these wrap up things. Can anybody suggest me any better way of doing it?

    I can not use C++ at this moment.

    Let me know

  2. #2
    ATH0 quzah's Avatar
    Join Date
    Oct 2001
    Posts
    14,826
    Code:
    h1 = CreateFile(..,..,..);
    h2 = CreateFile(..,..,..);
    h3 = CreateFile(..,..,..);
    h4 = CreateFile(..,..,..);
    
    if( h1 == false || h2 == false || h3 == false || h4 == false )
    {
        if( h1 ) Close( h1 );
        if( h2 ) Close( h2 );
        if( h3 ) Close( h3 );
        if( h4 ) Close( h4 );
        Exit;
    }
    
    ... do stuff ...
    Something like that would work.

    Quzah.
    Hope is the first step on the road to disappointment.

  3. #3
    End Of Line Hammer's Avatar
    Join Date
    Apr 2002
    Posts
    6,231
    Or how about an array approach:
    Code:
    #include <stdio.h>
    #include <stdlib.h>
    
    int main(void)
    {
      FILE *fp[10];
      int i;
      char buf[BUFSIZ];
      
      for (i = 0; i < 10; i++)
      {
        sprintf (buf, "file%d.txt", i);
        if ((fp[i] = fopen(buf, "r")) == NULL)
          break;
      }
      
      if (i != 10)
      {
        /* A file failed to open, close all previously opened files */
        perror(buf);
        while (i)
        {
          fclose(fp[--i]);
          printf ("Closed file %d\n", i);
        }
        return EXIT_FAILURE;
      }
      puts ("All files opened");
      
      /* Now use the files, then close them before finishing */
      return 0;
    }
    
    /* 
     Example output:
     
     file5.txt: No such file or directory
     Closed file 4
     Closed file 3
     Closed file 2
     Closed file 1
     Closed file 0
    
    */
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

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