question about sprintf()

This is a discussion on question about sprintf() within the C Programming forums, part of the General Programming Boards category; I have another simple question. say for example my code looks like this: Code: char str[10] = "abcdef"; sprintf(str, "%c", ...

  1. #1
    Madly in anger with you
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    question about sprintf()

    I have another simple question.

    say for example my code looks like this:

    Code:
    char str[10] = "abcdef";
    sprintf(str, "%c", 'g');
    what will happen to the original contents of str? will g be appended to them or will they be cleared?


    thank you in advance!

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  2. #2
    ATH0 quzah's Avatar
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    Why don't you compile it and find out? Actually all you have to do is put a few seconds of thought into it. Or you could just hilight your function call to sprintf in the IDE you're posting in your sig, and press something like F1, and get the detailed help on the function itself. Assuming of course you have installed the MSDN installed. Surely with your boast of the Enterprise Edition, you have the MSDN. I mean it's not like you pirated it or anything, right?


    Quzah.
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  3. #3
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    lol

    I checked msdn, it doesn't answer my question.

    the below printed g on the screen, so I guess it clears the original contents.

    Code:
    #include <stdio.h>
    
    int main(void)
    {
       char str[10] = "abcdef";
    
       sprintf(str, "%c", 'g');
       printf(str);
    
       return 0;
    }
    sorry, I won't post my very simple questions here again.

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  4. #4
    ATH0 quzah's Avatar
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    It doesn't clear it. It copies what you tell it to into the array. Since it's a string, it terminates it with a null character. Print the array a character at a time and you'll see it doesn't get cleared at all.

    It (the MSDN) does tell you what it (sprinft) does. Read:
    The sprintf function formats and stores a series of characters and values in buffer. Each argument (if any) is converted and output according to the corresponding format specification in format. The format consists of ordinary characters and has the same form and function as the format argument for printf. A null character is appended after the last character written. If copying occurs between strings that overlap, the behavior is undefined.
    You can post simple questions, it's just that you'll find it often faster, and a better learning experience, to try it yourself.

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

  5. #5
    Frequently Quite Prolix dwks's Avatar
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    If you want to append to the string, try:
    Code:
    char str[10] = "abcdef";
    sprintf(str+strlen(str), "%c", 'g');
    dwk

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