need to read a User defined file during runtime

This is a discussion on need to read a User defined file during runtime within the C Programming forums, part of the General Programming Boards category; Hi, basically what I have to do is write a filter program that opens a file for reading. This file ...

  1. #1
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    need to read a User defined file during runtime

    Hi,
    basically what I have to do is write a filter program that opens a file for reading. This file is User defined during runtime.
    Anybody got any ideas on how to do this??

  2. #2
    and the hat of wrongness Salem's Avatar
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    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  3. #3
    Code Goddess Prelude's Avatar
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    Code:
    char filename[FILENAME_MAX];
    FILE *fp;
    
    printf ( "File to open: " );
    fflush ( stdout );
    if ( fgets ( filename, sizeof filename, stdin ) != NULL ) {
      char *newline = strrchr ( filename, '\n' );
      if ( newline != NULL )
        *newline = '\0';
      fp = fopen ( filename, "r" );
      if ( fp == NULL )
        perror ( NULL );
      ...
    }
    My best code is written with the delete key.

  4. #4
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    Prelude,
    sorry but when I try to use your code the complier gives two errors

    [C++ Error] DUMPFILE.cpp(47): E2268 Call to undefined function 'strrchr'.

    [C++ Error] DUMPFILE.cpp(47): E2034 Cannot convert 'int' to 'char *'.

    for this line of code

    char *newline = strrchr ( filename, '\n' );

    any ideas??

    thanks

  5. #5
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    woops

    just got it to work,
    my fault forgot to add in string.h

    thanks for taking the time to help me out

  6. #6
    ATH0 quzah's Avatar
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    Originally posted by john_newbie
    the complier gives two errors

    [C++ Error] DUMPFILE.cpp(47): E2268 Call to undefined function 'strrchr'.

    [C++ Error] DUMPFILE.cpp(47): E2034 Cannot convert 'int' to 'char *'.

    any ideas??
    Here's an idea, try compiling as C instead of C++. That'll help with other issues later on that you'll end up asking about.

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

  7. #7
    c99
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    John.

    Code:
    /*
    	Simple file open/close program in C.
    
    	Error checking omitted for sanity.
    */
    #include <stdio.h>
    
    int main(int argc, char **argv)
    {
    	FILE* fptr;				/* File object...	*/
    
    
    	if (argc != 2)				/* Display usage.	*/
    	{
    		printf("Usage: %s [filename]\n", argv[0]);
    	}
    	else
    	{
    		fptr = fopen(argv[1], "r");	/* Open file...		*/
    
    		printf("%s opened for reading.\n", argv[1]);
    
    		fclose(fptr);			/* Close file...	*/
    
    		printf("%s closed.\n", argv[1]);
    	}
    	return 0;
    }
    R.I.P C89

  8. #8
    Code Goddess Prelude's Avatar
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    >Error checking omitted for sanity.
    I can understand your reasoning, but it really is better to assume that the people here are not stupid. If you post bulletproof code then it sets a good example.
    My best code is written with the delete key.

  9. #9
    and the hat of wrongness Salem's Avatar
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    Off-topic bickering snipped
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

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