c - 带有图形的程序被中止，即使调用了 XInitThreads

Question

我刚开始在 C 中使用 Graphics，在运行一个简单的绘制同心圆的程序时遇到了这个错误:

user@user:~/Documents/C$ gcc circle.c -lX11 -lgraph
user@user:~/Documents/C$ ./a.out
[xcb] Unknown sequence number while processing queue
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting, sorry about that. a.out: ../../src/xcb_io.c:274: poll_for_event:
      Assertion '!xcb_xlib_threads_sequence_lost' failed.
Aborted (core dumped)

和:

[xcb] Unknown sequence number while processing queue
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting, sorry about that. a.out: ../../src/xcb_io.c:274: poll_for_event: Assertion `!xcb_xlib_threads_sequence_lost' failed.

我在互联网上查找了一些论坛，他们建议添加 #include<X11/Xlib.h>并调用 XInitThreads()在main()的开头会解决问题，但我在运行时仍然遇到相同错误。

我附上了代码:

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

int main()
{
    XInitThreads();
    int gd=DETECT, gm,r,x;
    initgraph(&gd,&gm,NULL);

    setbkcolor(WHITE);
    setcolor(BLACK);
    for(r=10;r<100;r+=10)
    {
        circle(150,150,r);
    }
    scanf("%d",&x);
    closegraph();

    return 0;
}

我使用 Ubuntu 14.04 和 GCC 进行编译。

Answer 1

我在 closegraph() 之前添加了以下调用；

wait_for_char();

哪里:

void wait_for_char()
{

    //Wait for a key press
    int in = 0;

    while (in == 0) {
        in = getchar();
    }
}

这无需调用 XInitThreads() 即可解决问题。不要问我为什么。但我还是使用 wait_for_key() 给我时间看!