i dont want my nulls

This is a discussion on i dont want my nulls within the C Programming forums, part of the General Programming Boards category; hello everyone!! i need a little help if somebody can oblige. I'm trying to copy one small string into a ...

  1. #1
    Registered User the bassinvader's Avatar
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    Smile i dont want my nulls

    hello everyone!!
    i need a little help if somebody can oblige.

    I'm trying to copy one small string into a much larger one several times over
    using strcat(). This works fine however it also includes the \0 on the end of the
    shorter string. I would like to remove this if possible.
    Can somebody suggest a way of doing this or direct me to the 'how to' which i
    know i've seen somewhere on this very subject.

    Thanx

  2. #2
    Just Lurking Dave_Sinkula's Avatar
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    Could you post code and a sample input/output that shows exactly what you are doing -- and what you want to do? And please use [code][/code] tags.
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

  3. #3
    Registered User Tonto's Avatar
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    strcat only functions on null terminated strings. You would have to write your own routine to do this, keeping track of your place in the larger string, because you would not be able to just seek to the end like you would be able to with a null-terminated string. I can't see why you wouldn't want a null-terminated string for this.

  4. #4
    Code Goddess Prelude's Avatar
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    I don't understand your problem. strcat will overwrite the existing null character when it concatenates the new string. There shouldn't be any problem unless you're not working with strings, in which case strcat is the wrong solution. memcpy would be better.
    My best code is written with the delete key.

  5. #5
    Devil's Advocate SlyMaelstrom's Avatar
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    Quote Originally Posted by the bassinvader
    This works fine however it also includes the \0 on the end of the
    shorter string.
    Are you sure? It shouldn't. The function strcat() copies over the null at the end of the string being copied to.
    Code:
    #include <stdio.h>
    #include <string.h>
    
    int main(void) {
       char sString[] = "Hello";
       char lString[41];
       
       strcpy(lString,sString);
       
       while(strlen(lString) + strlen(sString) < 40) {
          strcat(lString, sString);
       }
       
       printf("%s", lString);
       
       return 0;
    }
    /*
      [H][e][l][l][o][\0]  ... strcpy ...
                     [H][e][l][l][o][\0]  ... giving you ...
      [H][e][l][l][o][H][e][l][l][o][\0]
    */
    ...and a billion people already replied. Note to self: Write shorter examples.
    Sent from my iPadŽ

  6. #6
    Registered User the bassinvader's Avatar
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    well maybe i've asked the wrong question to solve the problem!

    i want to take a short string like this:
    " a short string "

    and copy it into a larger string so it looks like this:

    " a short stringa short stringa short stringa short string "

    however at the moment when i 'printf' my long string i get this:


    a short string
    a short string
    a short string
    etc


    [code]

    int i;
    char longstring[100]; /*holds nothing to start*/
    char short[20]="a short string";

    strcpy(longstring,short);

    int mon;
    for(mon=0;mon<=(int)i;mon++)
    {
    strcat(longstring,short);
    }


    [\code]

    this code does exactly what i want. However if i get the code from the user and dont know the length
    of the string i get the problem.

  7. #7
    The Richness... Richie T's Avatar
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    The problem sounds like you are reading in a string using fgets or some other
    function which reads in a newline. It's quite easy to get rid of the newline,
    see my sig for a link on how to use fgets in that manner.

    the code you posted has an error:

    for(mon=0;mon<=(int)i;mon++)

    variable "i" is uninitialised at this point. You also didn't use code tags properly,
    it's a /, not a \ to terminate the tags!

    >>dont know the length of the string...

    You can use strlen to get the length of a string, in case you didn't know already.
    No No's:
    fflush (stdin); gets (); void main ();


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