如何查找表达式的哪个索引与正则表达式匹配

问题描述：

如何修改此代码以便它找到正则表达式匹配的索引。基本上假设我有“金”作为我的测试表达。我的测试字符串是“jkimsdfs”。我怎么能证明“jkimsdfs”在索引与“金”匹配1.如何查找表达式的哪个索引与正则表达式匹配

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

int main() { 

     char word[100]; //sets the limit of characters within word to 99(0-99 

     char exp[100]; //sets the limit of characters within exp to 99(0-99) 

     regex_t w; //contains size_t. This field holds the number of 
     //parenthetical subexpressions in the regular expression that was compiled. 

     int status; // integer status 

     printf("Test Expression: "); //print "Test Expression" 

     fgets(word,100,stdin); // 

     word[strlen(word)-1] = '\0'; 
     status = regcomp(&w,word,REG_EXTENDED|REG_NOSUB); 
     printf("%d\n", status); 
     printf("Validity of regex, if 0 than it matches: %d\n",status); 
     if (status) return 1; 
     while (1) { 
      printf("Test String: "); 
      fgets(exp,100,stdin); 
      exp[strlen(exp)-1] = '\0'; 
      if (strlen(exp) < 1) 
      break; 
      status = regexec(&w,exp,(size_t)0,NULL,0); 
      printf("Matched: %d\n",status); 
      printf("%d\n", status); 
      } 
      regfree(&w); 
     return 0; 
     }

阅读['man regcomp']（http://man7.org/linux/man-pages/man3/regex.3.html）以了解REG_NOSUB的作用，然后将其从代码中移除。 – melpomene

另外，不是将[0]，NULL传递给['regexec（）']（http://man7.org/linux/man-pages/man3/regexec.3.html），而是传入元素的个数， 'regmatch_t'的数组。数组中的初始元素将代表整个匹配。 –

答

您可以使用strstr：

char str[] = "jkimsdfs"; 
char *ptr; 

if ((ptr = strstr(str, "kim"))) { 
    if ((ptr - str) == 1) { 
     /* Match */ 
    } 
}

答

也许文档说得到匹配的位置将是

size_t  nmatch = 2; 
regmatch_t pmatch[2]; 

status = regexec(&w, exp, nmatch, pmatch, 0); 
if (status == 0) 
{ 
    printf("Matched \"%.*s\" at position %d.\n", 
     pmatch[1].rm_eo - pmatch[1].rm_so, &exp[pmatch[1].rm_so], 
     pmatch[1].rm_so); 
} 
else 
    printf("Match not found\n");

如何查找表达式的哪个索引与正则表达式匹配

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