problem with fgets

This is a discussion on problem with fgets within the C Programming forums, part of the General Programming Boards category; Hi all, can anybody help me solve the problem below? If I enter a string with a string length of ...

  1. #1
    Registered User
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    Mar 2005
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    20

    problem with fgets

    Hi all, can anybody help me solve the problem below? If I enter a string with a string length of more than 10 for inputString, the next fgets will just take what is stored in the buffer. I searched the forum for problems with fgets, but only found out that if i use fgets, and if it exceeds the buff size, the next fgets will pick up what is left from the first fgets. How can I solve this? Thank you.

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #define MAXSIZE 10
    
    int main(void)
    {
       char *inputString, *inputValue;
       
       inputString = malloc(MAXSIZE);
       inputValue = malloc(MAXSIZE);
       
       if(inputString==NULL)
       {
          fprintf(stderr, "Unable to allocate memory");
          exit(1);
       }
       
       if(inputValue==NULL)
       {
          fprintf(stderr, "Unable to allocate memory");
          exit(1);
       }
    
       printf("Please enter a string: ");
       fgets(inputString, MAXSIZE, stdin);
       
       printf("Input a value: ");
       fgets(inputValue, MAXSIZE, stdin);
       
       free(inputString);
       free(inputValue);
       
       return 0;
    }

  2. #2
    Registered User hk_mp5kpdw's Avatar
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    Location
    Northern Virginia/Washington DC Metropolitan Area
    Posts
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    Easiest solution... you probably should increase MAXSIZE to a level you feel will help you accommodate the largest possible string that would ever be entered by the user. If you anticipate the user may sometimes enter up to 30 characters, then you should make MAXSIZE at least 31 (+1 for the NULL) for example.

    Alternately, switch to using a C++ string container. They would allow strings of any arbitrary length to be entered.
    "Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
    -Christopher Hitchens

  3. #3
    ATH0 quzah's Avatar
    Join Date
    Oct 2001
    Posts
    14,826
    Code:
    while( fgets( buf, BUFSIZ, fp ) )
    {
        if( strchr( buf, '\n' ) )
            break;
    
        ...otherwise, realloc some space, strcat this buffer onto it...
    }
    Something like that should suffice.

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

  4. #4
    Registered User
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    Mar 2005
    Posts
    20
    Ok, I got it, thanks guys!

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