c - 确定 C 缓冲区中的多个空格分隔的输入

Question

在为我的命令解释器读取输入时，我一直在努力证明我的逻辑。我遇到的问题是 strstr() 要么不接受 "%s" 作为针，要么正在处理整个 haystack 作为字符串，因此忽略空格、换行符等。

char command[4] = "";
char arg1[512] = "";
char arg2[512] = "";
char tmp[1029] = "";
char buffer[BUFFERSIZE];
memset(buffer, '\0', BUFFERSIZE);

while(fgets(buffer, BUFFERSIZE, stdin) != NULL){
    strcpy(command, "");
    strcpy(arg1, "");
    strcpy(arg2, "");
    strcpy(tmp, "");
    if(strstr(buffer, "%s\n") != NULL)
        sscanf(buffer, "%s", command);  // 0 arguments
    if(strstr(buffer, "%s %s") != NULL)
        sscanf(buffer, "%s", arg1);     // 1 argument
    if(strstr(buffer, "%s %s %s") != NULL)
        sscanf(buffer, "%s", arg2);     // 2 arguments
    printf("%s %s %s\n", command, arg1, arg2);
}

无论我输入什么:

• com
• val argument1val
• 命令 arg1 arg2val
• 等等

对于 command、arg1 和 arg2，我总是以空字符数组结束。

我的输入将始终是单个字符串或最多三个空格分隔的字符串，后跟一个换行符。

Answer 1

您只需扫描一次并检查 sccanf 返回的已解析参数的数量(特别检查输入的空行)

#include <stdio.h>
#include <strings.h>

#define BUFFERSIZE 2000

int main()
{
int nb_args;
char command[4] = "";
char arg1[512] = "";
char arg2[512] = "";
char buffer[BUFFERSIZE];
memset(buffer, '\0', BUFFERSIZE);

while(fgets(buffer, BUFFERSIZE, stdin) != NULL){
    strcpy(command, "");
    strcpy(arg1, "");
    strcpy(arg2, "");

    nb_args = sscanf(buffer, "%3s%511s%511s", command,arg1,arg2);
    if (strlen(command)==0)
    {
        printf("empty line\n");
    }
    else
    {
    switch(nb_args)
    {
        case 1:
           printf("Command = %s\n",command);
           break;
        case 2:
           printf("Command = %s, arg1 = %s\n",command,arg1);
           break;
        case 3:
           printf("Command = %s, arg1 = %s, arg2 = %s\n",command,arg1,arg2);
           break;
    }
    }
}
}