fprintf isn't outputting anything to file

This is a discussion on fprintf isn't outputting anything to file within the C Programming forums, part of the General Programming Boards category; I am trying to use the following c code to print out an array that I have passed in. It ...

  1. #1
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    fprintf isn't outputting anything to file

    I am trying to use the following c code to print out an array that I have passed in. It should output the text in hexadecimal format one on each line. When I first wrote it, I had no problems with it working I opened the output file and my array was there. I changed the fileOutName parameter and now I can't get it to print out anything. Any help would be appreciated. Thanks

    Code:
     printoutput(int  output[],char * fileOutName){
        int i=0;
        FILE * pOutfile;
        pOutfile = fopen( fileOutName, "w" );
        while(output[i]!=0){
            fprintf( pOutfile, "0x%0.4X\n", output[i]);
            i++;
    }
    Last edited by RagingPenguin4; 09-16-2012 at 07:04 PM.

  2. #2
    - - - - - - - - oogabooga's Avatar
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    Your fprintf has a constant 5 as the output value. You probably want (and probably had before) output[i] there.

    Shouldn't you check that the file opened properly?

    Shouldn't you close the file before returning from the function?

    Your while loop is a perfect candidate for a for loop.
    The cost of software maintenance increases with the square of the programmer's creativity. - Robert D. Bliss

  3. #3
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    Sorry the 5 was an something that I had for testing that I didn't realize was there but I put the output[i] back in its place where it should be. I would have used a for loop but I didn't have the array length

  4. #4
    - - - - - - - - oogabooga's Avatar
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    Try this. Does it work? If not, what happens?
    Code:
    void printoutput(int output[], char *fileOutName) {
        int i;
        FILE *pOutFile = fopen(fileOutName, "w");
        if (pOutFile == NULL) {
            fprintf(stderr, "fopen failed\n");
            exit(1);
        }
        for (i=0; output[i]!=0; i++)
            fprintf(pOutfile, "0x%0.4X\n", output[i]);
        fclose(pOutFile);
    }
    Last edited by oogabooga; 09-16-2012 at 08:09 PM. Reason: added beginning brace
    The cost of software maintenance increases with the square of the programmer's creativity. - Robert D. Bliss

  5. #5
    TEIAM - problem solved
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    Hey oogabooga - I think that you may have missed an opening '{' at the start of the function.
    Fact - Beethoven wrote his first symphony in C

  6. #6
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    Quote Originally Posted by Click_here View Post
    Hey oogabooga - I think that you may have missed an opening '{' at the start of the
    function.
    Thanks click. I've fixed it.
    The cost of software maintenance increases with the square of the programmer's creativity. - Robert D. Bliss

  7. #7
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    Hmm not sure why that fixed it but at least it works now. On a semi-related note whenever I make that function void, Visual studios doesn't like it however it isn't returning anything :/
    Thanks!

  8. #8
    C++ Witch laserlight's Avatar
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    What compiler error/warning do you get?
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  9. #9
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    error C2371: 'printoutput' : redefinition; different basic types
    Although i think i figured it out, in my prototype I had left out the return type and I am assuming (can't remember exactly) that the default return type is an int so when I declared it void it clashed with the prototype.

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