setting array to 0

This is a discussion on setting array to 0 within the C Programming forums, part of the General Programming Boards category; Hello everyone, I'm learning about code used to open files. I got the following code from "Sam's Teach Yourself C ...

  1. #1
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    Feb 2005
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    19

    setting array to 0

    Hello everyone,

    I'm learning about code used to open files.

    I got the following code from "Sam's Teach Yourself C for Linux Programming"

    I don't understand why he set filename[ ] and mode [ ] to 0.
    Code:
    /*demonstrating the fopen( )*/
    #include <stdlib.h>
    #include <stdio.h>
    
    int main(void)
    {
       FILE *fp;
       char ch, filename[40], mode[5];
    
       while (1)
    
       {
            printf("\nEnter a filename: ");
            fgets(filename, 40, stdin);
            filename[ strlen(filename) - 1] = 0;  /*sets filename[ ] to 0 ????*/
            printf("\nEnter a mode (max 3 characters): ");
            fgets(mode, 5, stdin);
            mode [ strlen(mode) - 1] = 0; /*sets mode[ ] to 0 ????*/
    
            /*then opens file with--- */
    
             if ( ( fp = fopen( filename, mode ) ) != NULL )
    
          /* etc. .....*/
    Thanks

  2. #2
    Frequently Quite Prolix dwks's Avatar
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    Canada
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    Code:
    mode [ strlen(mode) - 1] = 0;
    This will strip the newline off of mode. fgets() sometimes adds a newline onto the end.

    It should really be
    Code:
    if(mode[strlen(mode)-1] == '\n') mode[strlen(mode)-1] = 0;
    dwk

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  3. #3
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    Feb 2005
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    That has to be the fastest response I have ever had on a post.
    (less than 5 minutes)
    Thanks!

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