check if the file exists

This is a discussion on check if the file exists within the C Programming forums, part of the General Programming Boards category; how do i check if a file exist? without using if (fopen(....));...

  1. #1
    ipe
    ipe is offline
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    Jan 2003
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    check if the file exists

    how do i check if a file exist?

    without using if (fopen(....));

  2. #2
    .........
    Join Date
    Nov 2002
    Posts
    303
    Im not sure if there is a function that does this. But this would work using fopen.
    Code:
    #include <stdio.h>
    
    int
    main(void)
    {
    
    	if (fopen("filename.txt", "r") == NULL) {
    		printf("You know the file doesn't exist\n");
    	}
    	else {
    		printf("File exists\n");
    	}
    
    	return (0);
    }
    fopen returns NULL on error, and a FILE pointer on success. So in this case if fopen returns NULL you know that there is no file, otherwise fopens returns a FILE pointer and nothing happens. If your still confused you can read here to learn more about fopen and about how it works.

  3. #3
    Code Goddess Prelude's Avatar
    Join Date
    Sep 2001
    Posts
    9,796
    >how do i check if a file exist?
    The only portable way is to try and open it for reading. If the operation fails then it's a good bet that the file doesn't exist.

    >without using if (fopen(....));
    In that case, it depends on your operating system and compiler, for example, this would work if your system supports it:
    Code:
    #include <sys/stat.h>
    #include <unistd.h>
    #include <stdlib.h>
    #include <stdio.h>
    #include <errno.h>
    
    int main ( void )
    {
      struct stat buf;
    
      errno = 0;
      if ( stat ( "somefilename", &buf ) != 0 && errno == ENOENT ) {
        fprintf ( stderr, "File or file path does not exist\n" );
        exit ( EXIT_FAILURE );
      }
    
      return EXIT_SUCCESS;
    }
    -Prelude
    My best code is written with the delete key.

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