[SOLVED] x11 programming::cannot printf::bug of printf？？

[fyplinux]

Hi,

I am currently learning to program with the X11 lib, I met a problem that the printf function couldn't work until X11 is broken.


below is the code
================================

#include <X11/Xlib.h>
#include <stdio.h>
#include <stdlib.h>

int main(void){

Display *d; int s; Window w; XEvent ev;
int should_quit = 0;

d = XOpenDisplay(NULL);
s = XDefaultScreen(d);

w = XCreateSimpleWindow(d, XRootWindow(d, s), 0, 0,
200, 200, 0,
XBlackPixel(d, s),
XWhitePixel(d, s));

XSelectInput(d, w, ButtonPressMask);
XMapWindow(d, w);

printf("dfdfdsfs");/*printf is called here*/


while(!should_quit)
{
XNextEvent(d, &ev);
switch(ev.type)
{
case ButtonPress:
should_quit = 1;
break;
default:
break;
}
}

return 0;
}


when I closed the window, the output of the terminal was
=============================
X connection to :0.0 broken (explicit kill or server shutdown).
dfdfdsfs


But, if the printf call is coded like:
printf("dfdfdsfs\n");

the program works properly, here is the output
==============================
dfdfdsfs
X connection to :0.0 broken (explicit kill or server shutdown).



The question is why printf cannot work properly without the newline endian?

thanks.

[DMills]

This is not an X11 question, but one of C...

Printf writes to the stdout stream, which by default is buffered[1], you can flush the buffer with fflush or by writing a newline (or you can set the stream to non buffered with the setvbuf call).

Regards, Dan.

[1]Line buffered if it is connected to a terminal, else just buffered, the line buffering is why \n works, and all buffers are flushed on exit which is why you see the first case.

[gnusci]

Yes thats right just try flushing the stdout as follow:


printf("dfdfdsfs");/*printf is called here*/
fflush(stdout);

[fyplinux]

Yes thats right just try flushing the stdout as follow:


printf("dfdfdsfs");/*printf is called here*/
fflush(stdout);

yes, it works!

Thank you.