neverending loop

This is a discussion on neverending loop within the C Programming forums, part of the General Programming Boards category; Hey guys i have the following code it reads a text file and list numbers to each word line. example: ...

  1. #1
    Musicman - Canora
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    Location
    Melbourne
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    neverending loop

    Hey guys i have the following code it reads a text file and list numbers to each word line. example:

    1. abfdfd
    2. hello world
    3
    4 so on..

    but at the moment its only listing the numbers and in a neverending loop so i have no idea whats going on.



    Code:
    #include <stdio.h>
    #include <stdlib.h>
    
    int main(int argc, char **argv)
    {
    
        int line_no = 0;
        int input_char = 0;
        int nl = 0;
        FILE *fp;
    
        if(argc !=2) /* check for 2 arguments*/
        {
    
          fprintf(stderr, "invalid usage :%s\n", argv[0]);
          return 1; /* stop processing if failes */
    
        }
    
        if((fp = fopen(argv[1], "r")) == NULL) 
        /* opens file for reading and checks if it exists */
        {
         
         fprintf(stderr, "invalid usage: %s\n", argv[0]);
         return 1; /* stop processing if fails*/
    
        }
    
    
          while(input_char !=EOF)
     
              /* keep asking for input while not end of file*/
          {
              if ( nl )
              {
                 printf("\n%d ", line_no);
                 line_no++;
    	  }
    	  else
              { 
    	     putc(input_char, stdout);
    	     input_char = getc(fp);   
    	     nl = input_char == '\n';
              }
        }
           
        
    
        fclose(fp);
    
    
    
        return EXIT_SUCCESS;
    
    }

  2. #2
    cwr
    cwr is offline
    Registered Luser cwr's Avatar
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    Are you a goldfish?

    You already posted the same question earlier, I answered it:

    while loop trouble

    The solution, partially, is to set nl to 0 again after you print the \n for a newline.
    Last edited by cwr; 09-19-2005 at 08:15 AM.

  3. #3
    Musicman - Canora
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    Ok yehhhh i did intialize it to zero but why does it still loop

  4. #4
    cwr
    cwr is offline
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    No, you need to set it to 0 here:
    Code:
    if ( nl )
    {
        printf("\n%d ", line_no);
        line_no++;
        nl = 0;
    }
    Otherwise as soon as you hit the first newline, it will be permantly stuck in the "found a new line" state.

  5. #5
    Registered User
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    Aug 2005
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    1,267
    You are doing that the hard way. use fgets() and you don't have to worry about EOF.
    Code:
    char line[255];
    int line_counter = 1;
    while(fgets(line,sizeof(line),fp) != 0)
    {
       printf("%d%s", line_counter++,line);
    }

  6. #6
    kiddo
    Join Date
    Sep 2005
    Posts
    8
    hi bazzano,

    here is the solution for ur ques. im new to this website and to file handling. i have solved it with watever i know.
    hope u like it.

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    
    int main(int argc, char **argv)
    {
    
        int line_no = 1;
        char input_char;
        FILE *fp;
        clrscr();
        if(argc !=2) /* check for 2 arguments*/
        {
    
          fprintf(stderr, "invalid usage :%s\n", argv[0]);
         return 1; /* stop processing if failes */
    
        }
    
        if((fp = fopen(argv[1],"r")) == NULL)
        /* opens file for reading and checks if it exists */
        {
    
         fprintf(stderr, "invalid usage: %s\n", argv[0]);
         return 1; /* stop processing if fails*/
    
        }
         printf("\n%d. ", line_no);
         while(input_char!=EOF)
    	  /* keep asking for input while not end of file*/
          {
          input_char = getc(fp);
          if(input_char=='\n')
    	  {
    	  line_no++;
    	  printf("\n%d. ", line_no);
    	  }
    	     if(input_char!='\n')
    	     putc(input_char, stdout);
    
        }
           printf("\b\b\b\b  \b\b");
        fclose(fp);
       return EXIT_SUCCESS;
    }

  7. #7
    ATH0 quzah's Avatar
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    Oct 2001
    Posts
    14,826
    Quote Originally Posted by mitto123
    hi bazzano,

    here is the solution for ur ques. im new to this website and to file handling. i have solved it with watever i know.
    hope u like it.

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    
    int main(int argc, char **argv)
    {
    
        int line_no = 1;
        char input_char;
    
    
         while(input_char!=EOF)
    	  /* keep asking for input while not end of file*/
    Read the EOF FAQ as to why this is wrong.


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

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