小编flo*_*bue的帖子

我最近读了一些st终端源代码.在那里我找到了这段代码:

switch (csiescseq.mode[0]) {
default:
unknown:
    fprintf(stderr, "erresc: unknown csi ");
    csidump();
    /* die(""); */
    break;
case '@': /* ICH -- Insert <n> blank char */

"未知"关键字(？)有什么作用？我无法在任何地方找到任何"未知"关键字.感谢您的建议.

Why does gcc ignore these header guards in this simple test program?

The header file is:

#ifndef MYHEADER_H
#define MYHEADER_H

#warning "header declared"

int some_int=0;

#endif

And the two .c files are: main.c:

#include "header.h"

int main ()
{
    return some_int;
}

source.c:

#include "header.h"

int get_int()
{
    return some_int;
}

When compiling with:

  gcc -o out main.c source.c

I get the following output:

In file included from main.c:1:
header.h:4:2: warning: #warning "header declared" [-Wcpp]
    4 | #warning "header declared" …