fprintf in void function Not Printing

This is a discussion on fprintf in void function Not Printing within the C Programming forums, part of the General Programming Boards category; I have a function call in my main function. It is suppose to be a progress reporter. Each time the ...

  1. #1
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    fprintf in void function Not Printing

    I have a function call in my main function. It is suppose to be a progress reporter. Each time the function is called, as shown below, the progress is to be printed on the screen.
    Code:
    loop_counter(&loop_count, some_constant);
    The function body looks like the following:
    Code:
    void loop_counter(long long *loop_count, long long some_constant)
    {
    *loop_count++;
    if(*loop_count % 40000 == 0 || *loop_count == some_constant)
    fprintf(stderr,"\r %d %% done ", (long long)(100.0*(double)(*loop_count)/(double)some_constant));
    }
    For some reason, nothing gets printed on the screen. Can anyone tell me why this is?

  2. #2
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    >fprintf(stderr,"\r %d
    To print a long long, use either %lld, or if that doesn't work, %I64d.
    Code:
    fprintf(stderr,"\r %I64d %% done ", (long long)(100.0*(double)(*loop_count)/(double)some_constant));
    If nothing at all is being printed, then the if condition isn't being met. You would have to show us what loop_counter and some_constant are at this call:
    >loop_counter(&loop_count, some_constant);

  3. #3
    Frequently Quite Prolix dwks's Avatar
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    MSVC 6 doesn't have support for long longs in its standard C library, but Dev-C++ and others do. MSVC treats it like a long, so if you don't exceed the limits of a long, it should work even there.
    dwk

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  4. #4
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    If I replace
    Code:
    loop_counter(&loop_count, some_constant);
    in my main() function with
    Code:
    loop_count++;
    if(loop_count % 40000 == 0 || loop_count == totalN)
    fprintf(stderr,"\r %d %% done ", (long long)(100.0*(double)loop_count/(double)totalN));
    then everything works fine. I don't think the problem is the %d or the long long. The problem is that nothing at all gets printed to the screen.

  5. #5
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    Based on the code you just posted, then here:
    >*loop_count++;
    What you really want is:
    Code:
    (*loop_count)++;

  6. #6
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    Thanks. That did it

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