GCC编译并行端口脉冲控制C代码出现错误求助

问题概述 #

在Debian 12（Bookworm）系统中，编译用于通过并行端口控制步进电机的C文件primeroscomandos.c时，执行gcc primeroscomandos.c出现编译错误，错误包含非法字符、perror函数参数指针类型不兼容等问题。

原代码 #

#include <stdio.h>
#include <stdlib.h>
#include <sys/io.h>
#include <unistd.h>

#define BASEPORT 0x378

int main()
{
    if(ioperm(BASEPORT, 3, 1))
    {
        perror(“ioperm”);
        return 1;
    }

    outb(0x01, BASEPORT);
    usleep(100000);

    outb(0x02, BASEPORT);
    usleep(1000000);

    outb(0x00, BASEPORT);
    if(ioperm(BASEPORT, 3, 0))
    {
        perror(“ioperm”);
        return 1;
    }

    return 0;
}

编译错误信息 #

primeroscomandos.c: In function ‘main’:
primeroscomandos.c:9:33: error: stray ‘\342’ in program
9 | if(ioperm(BASEPORT,3,1)){perror(<U+201C>ioperm<U+201D>);
  |                                 ^~~~~~~~
primeroscomandos.c:9:40: error: stray ‘\342’ in program
9 | if(ioperm(BASEPORT,3,1)){perror(<U+201C>ioperm<U+201D>);
  |                                               ^~~~~~~~
primeroscomandos.c:9:34: warning: passing argument 1 of ‘perror’ from incompatible pointer type [-Wincompatible-pointer-types]
9 | if(ioperm(BASEPORT,3,1)){perror(“ioperm”);
  |                                  ^~~~~~
  |                                  |
  |                                  int (*)(long unsigned int,  long unsigned int,  int)

In file included from primeroscomandos.c:1:

/usr/include/stdio.h:804:33: note: expected ‘const char *’ but argument is of type ‘int (*)(long unsigned int,  long unsigned int,  int)’
  804 | extern void perror (const char *__s);
      |                     ~~~~~~~~~~~~^~~
primeroscomandos.c:20:33: error: stray ‘\342’ in program
   20 | if(ioperm(BASEPORT,3,0)){perror(<U+201C>ioperm<U+201D>);
      |                                 ^~~~~~~~
primeroscomandos.c:20:40: error: stray ‘\342’ in program
   20 | if(ioperm(BASEPORT,3,0)){perror(<U+201C>ioperm<U+201D>);
      |                                               ^~~~~~~~
primeroscomandos.c:20:34: warning: passing argument 1 of ‘perror’ from incompatible pointer type [-Wincompatible-pointer-types]
   20 | if(ioperm(BASEPORT,3,0)){perror(“ioperm”);
      |                                  ^~~~~~                                  |
      |                                  int (*)(long unsigned int,  long unsigned int,  int)
/usr/include/stdio.h:804:33: note: expected ‘const char *’ but argument is of type ‘int (*)(long unsigned int,  long unsigned int,  int)’
  804 | extern void perror (const char *__s);
      |                     ~~~~~~~~~~~~^~~

错误原因分析 #

所有错误的根源是代码中使用了全角中文引号“”，而非C语言要求的半角英文引号""。编译器无法识别全角引号，会将其解析为非法的ASCII转义字符（如\342），同时误把引号包裹的ioperm识别为函数指针，而非字符串常量，导致perror参数类型不兼容。

修复后的代码 #

将所有全角引号替换为半角引号即可解决问题：

#include <stdio.h>
#include <stdlib.h>
#include <sys/io.h>
#include <unistd.h>

#define BASEPORT 0x378

int main()
{
    if(ioperm(BASEPORT, 3, 1))
    {
        perror("ioperm");
        return 1;
    }

    outb(0x01, BASEPORT);
    usleep(100000);

    outb(0x02, BASEPORT);
    usleep(1000000);

    outb(0x00, BASEPORT);
    if(ioperm(BASEPORT, 3, 0))
    {
        perror("ioperm");
        return 1;
    }

    return 0;
}

编译与运行说明 #

1. 编译命令：gcc primeroscomandos.c -o primeroscomandos
2. 由于ioperm需要直接访问硬件端口，必须以root权限运行程序：sudo ./primeroscomandos

内容的提问来源于stack exchange，提问作者M M