Question

我试图询问用户他们想要在＆＃34; shell＆＃34;我做过的。我的代码如下：

    /* Create a char array to hold response */
char response[80];
char exit[4] = "Exit";

printf("\n\n     Commands are as followed:");
printf("\n------------------------------------");
printf("\n'cd' 'Directory' (Changes Directorys)");
printf("\n'cp' 'FileName'  (Copys File)");
printf("\n'Exit'           (Exits the program)");
printf("\n'ls'             (Displays Info)");
printf("\n------------------------------------\n\n");

while(strcmp(exit, response) != 0){

/* Ask user for input */
fputs("$> ", stdout);

/* Flush */
fflush(stdout);

/* Make sure response is not NULL */
if ( fgets(response, sizeof response, stdin) != NULL )
{
    /* search for newline character */
    char *newline = strchr(response, '\n'); 
    if ( newline != NULL )
    {
        /* overwrite trailing newline */
        *newline = '\0'; 
    }

    actOnResponse(fs, response); 
 }

现在我的问题涉及actOnResponse（）函数。我想将响应传递给函数。在函数中，我将解析响应，并将字符串与值＆＃39; cd＆＃39;，＆＃39; cp＆＃39;进行比较。和＆＃39; ls＆＃39;。但是我该怎么做呢？现在，当我运行程序时，它给了我一个分段错误（Core Dump）。

任何可以指出我做错的人都会很棒！谢谢。

这是actOnResponse（）函数：

void actOnResponse(int fs, char *response){

printf("%s" , response);
}

Answer 1

初始化响应，例如响应[0] = 0。
退出长度为5（结束零）。使用char exit [] =＆＃34;退出＆＃34 ;;否则你的strncmp可能会失败。
fs未定义。

此代码有效：

#include <stdio.h>
#include <string.h>

void actOnResponse(int fs, char *response){
  printf("%s\n" , response);
}

void main() {
  /* Create a char array to hold response */
  char response[80];
  char exit[] = "Exit";
  int fs = 0;

  response[0] = 0;

  printf("\n\n     Commands are as followed:");
  printf("\n------------------------------------");
  printf("\n'cd' 'Directory' (Changes Directorys)");
  printf("\n'cp' 'FileName'  (Copys File)");
  printf("\n'Exit'           (Exits the program)");
  printf("\n'ls'             (Displays Info)");
  printf("\n------------------------------------\n\n");

  while (strcmp(exit, response) != 0) {
    /* Ask user for input */
    fputs("$> ", stdout);

    /* Flush */
    fflush(stdout);

    /* Make sure response is not NULL */
    if (fgets(response, sizeof response, stdin) != NULL) {
      /* search for newline character */
      char *newline = strchr(response, '\n');
      if (newline != NULL) {
        /* overwrite trailing newline */
        *newline = '\0';
      }
      actOnResponse(fs, response);
    }
  }
}

（保存为test.c。运行gcc -o test test.o然后./test）。

Answer 2

这里exit [4]不包含字符串结束字符（因为它不是exit [5]）而且response [80]也没有初始化，因此它也不包含字符串ecd charecter。

因此当它与 strcmp 一起使用时，它无法找到字符串的结尾并且内存不足则会出现此分段错误。

所以这是由于这个变量的组合。

Answer 3

阅读中的注释，原因可能是seg错误。

以下代码有效:(添加了遗失}与while声明配对）
通过以下小编辑，我从未见过seg错误。

void actOnResponse(int fs, char *response);


int main(void)
{
    char response[80]={0};
    //char exit[>>>4<<<] = "Exit";  //seg fault may have happened resulting from this line, 
                              //need space for 5, including `\0`  Otherwise, `exit` would not
                              //be legal string, potentially cause string functions such as
                              // strcmp() or stricmp() etc. to seg fault.

    char exitt[] = "Exit";  //conflict with my system, changed `Exit` to `Exitt` throughout

    printf("\n\n     Commands are as followed:");
    printf("\n------------------------------------");
    printf("\n'cd' 'Directory' (Changes Directorys)");
    printf("\n'cp' 'FileName'  (Copys File)");
    printf("\n'Exit'           (Exits the program)");
    printf("\n'ls'             (Displays Info)");
    printf("\n------------------------------------\n\n");

    while(strcmp(exitt, response) != 0){

    /* Ask user for input */
    fputs("$> ", stdout);

    /* Flush */
    fflush(stdout);

    /* Make sure response is not NULL */
    if ( fgets(response, sizeof response, stdin) != NULL )
    {
        /* search for newline character */
        char *newline = strchr(response, '\n'); 
        if ( newline != NULL )
        {
            /* overwrite trailing newline */
            *newline = '\0'; 
        }

        actOnResponse(1, response); //not sure what 1st argument is supposed to be, just used `1`
     }
    }  //This was missing 
    return 0;
}


void actOnResponse(int fs, char *response)
{
    printf("%s" , response);
}

如何将输入响应传递给C中的函数

3 个答案: