Where is the real problem ?

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Here is a C code

C++

{ // message block
        char *message = "SYSTEM_STATE_IDLE  ";
        OpenGL_text(message, -1, -1, 0);
        glFlush(); // needed
        int test_count = 0;
        printf("\n test count %i state %s @function  %s @line %i ", test_count++, message,__FUNCTION__,__LINE__);
        printf("\n test count %i state %s @function  %s @line %i ", test_count++, message,__FUNCTION__,__LINE__);
        printf("\n test count %i state %s @function  %s @line %i ", test_count++, message,__FUNCTION__,__LINE__);
        printf("\n test count %i state %s @function  %s @line %i ", test_count++, message,__FUNCTION__,__LINE__);

        glFlush(); // needed ??
    } // message block

The output to OpenGL (screen) is correct, the tracking printf is not.

And here is the incorrect output, assuming printf outputs to standard I/O.

test count 0 state SYSTEM_STATE_IDLE   @function  OpenGL_SystemState @line 4961 
 test count 1 state SYSTEM_STATE_IDLE   @function  OpenGL_SystemState @line 4962 
 test count 2 state SYSTEM_STATE_IDLE   @function  OpenGL_SystemState @line 4963

Where is count #3 ??

What I have tried:

I am using multiple printf because when I used only one there is NO output at all.

Posted 8-May-20 5:47am

Vaclav_

Updated 8-May-20 5:53am

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Patrice T · Accepted Answer · 2020-05-08T05:54:00

Solution 1

Quote:
Where is count #3 ??

Try

C++

int test_count = 0;
printf("\n test count %i state %s @function  %s @line %i ", test_count++, message,__FUNCTION__,__LINE__);
printf("\n test count %i state %s @function  %s @line %i ", test_count++, message,__FUNCTION__,__LINE__);
printf("\n test count %i state %s @function  %s @line %i ", test_count++, message,__FUNCTION__,__LINE__);
printf("\n test count %i state %s @function  %s @line %i ", test_count++, message,__FUNCTION__,__LINE__);
printf("\n");

Posted 8-May-20 5:54am

Patrice T

Comments

k5054 8-May-20 12:02pm

or fflush(stdout) if you don't want to move the cursor to a new line. I'd also say maybe use fputs(stdout, "\n"), so as not to incur the overhead of printf if you don't need to, but I've seen compilers optimize that out for at least 15 years, so its really a matter of taste.

Vaclav_ 8-May-20 17:46pm

OpenGL has a "feature" glFlush described as " force OpenGL to complete the previous code IMMEDIATELY" I am not interested in finding out why , but with current experience with printf and a suggestion to use fflush stdout it looks as this "flush stdout " has similar function. So if this is just another version of cout /cerr lacking synchronization with main process I guess "...And that's the way it is..." (W,Cronkite )

Vaclav_ 10-May-20 11:44am

Sorry folks, but the question was "why not all printf are executed?" . I did not spell it out correctly. It is not question of clearing / flushing, but question is why is it not executed in first place. "I am using multiple printf because when I used only one there is NO output at all."

Patrice T 10-May-20 12:07pm

Use Improve question to update your question.
So that everyone can pay attention to this information.

Vaclav_ 10-May-20 12:36pm

So me admitting that I did not post it the way people will interpret it as " why is the printf not executed" is my fault. Sorry , it is not my fault if people do not read REQUIRED " what did you try " unless I post "I did ask Mrs Google..." Give me a break. I do not ask to read in-between line, but (for) simple analysis....