在C中优雅地解析查询字符串

Question

我正在尝试解析C中的URL查询字符串,我不知道如何优雅地执行它.任何提示或建议将不胜感激:

static void readParams(char * string, char * param, char * value) {
    char arg[100] = {0};  // Not elegant, brittle
    char value2[1024] = {0};

    sscanf(string, "%[^=]=%s", arg, value2);
    strcpy(param, arg);
    strcpy(value, value2);
}
char * contents = "username=ted&age=25";
char * splitted = strtok (contents,"&");
char * username;
char * age;

while (splitted != NULL)
{
    char param[100]; // Not elegant, brittle
    char value[100];
    char * t_str = strdup(splitted);
    readParams(t_str, param, value);
    if (strcmp(param, "username") == 0) {
        username = strdup(value);
    }
    if (strcmp(param, "age") == 0) {
        age = strdup(value); // This is a string, can do atoi
    }
   splitted = strtok (NULL, "&");
 }

我一直存在的问题是因为strtok函数在最后一个strtok函数似乎打破了while循环之前似乎更聪明.

Answer 1

一般来说，strtok 会破坏源字符串以供其他一些函数使用。这是使用 strtok 标记字符串的简单示例

  #include <stdlib.h>
  #include <string.h>
  #include <stdio.h>
  #define MX_SPLIT 128
    char **split( char **result, char *working, const char *src, const char *delim)
    {
        int i;

        strcpy(working, src); // working will get chppped up instead of src 
        char *p=strtok(working, delim);
        for(i=0; p!=NULL && i < (MX_SPLIT -1); i++, p=strtok(NULL, delim) )
        {
            result[i]=p;
            result[i+1]=NULL;  // mark the end of result array
        }
        return result;
    }

    void foo(const char *somestring)
    {
       int i=0;
       char *result[MX_SPLIT]={NULL};
       char working[256]={0x0}; // assume somestring is never bigger than 256 - a weak assumption
       char mydelim[]="!@#$%^&*()_-";
       split(result, working, somestring, mydelim);
       while(result[i]!=NULL)
          printf("token # %d=%s\n", i, result[i]);
    }