Horace papa's life

fflush就是將output buffer的內容寫到file裡.那如果是fflush()就是寫到stdout.

Syntax:

#include <stdio.h>
int fflush( FILE *stream );

Description:
If the given file stream is an output stream, then fflush() causes the output buffer to be written to the file. If the given stream is of the input type, then fflush() causes the input buffer to be cleared. fflush() is useful when debugging, if a program segfaults before it has a chance to write output to the screen. Calling fflush( STDOUT ) directly after debugging output will ensure that your output is displayed at the correct time.

#include<stdio.h>
#include<unistd.h>

int main()
{
#if 1
        int i;
        for (i=0;i<10;i++)
        {
          printf("%d",i);
           fflush(stdout);
          sleep(1);
        }
#endif
        return 0;
}

如果有加fflush就會每執行一個for 回圈就印一次.如果沒有的話就會到跳出for迴圈後才印.