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由于C语言的正则表达式API相对比较简易.默认API只有regcomp/regerror/regexec/regfree这些函数.相对于其他的高级语言中正则表达式所所能实现的功能(如:查找/替换)有所欠缺.所以想着自己写下一些需要的函数以备后续需要使用.

#ifndef _E_REGEX_INCLUDE
#define _E_REGEX_INCLUDE
#include <regex.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>typedef int errno_t;static size_t position = 0;//functions prototype
char* regnext(regex_t* regex,char* content);
void _r_release(void);
bool regreplace(regex_t* regex,char** content,char* replacement);
void regreplaceAll(regex_t* regex,char** content,char* replacement);int main(void){char* content = (char*)"sjdlf12323ldjslfjsjf133334";char* pattern = (char*)"([[:digit:]][[:digit:]])\\1";regex_t regex;errno_t state = regcomp(&regex,pattern,REG_EXTENDED);if(state){char* errbuf = calloc(20,sizeof(char));regerror(state,&regex,errbuf,20);fprintf(stderr,"Regex:%s compile failed.\n""Reason: %s\n",pattern,errbuf);free(errbuf);regfree(&regex);exit(EXIT_FAILURE);}printf("content: %s\n",content);char* replacement = (char*)"";regreplaceAll(&regex,&content,replacement);printf("content: %s\n",content);regfree(&regex);
}//find next match
char* regnext(regex_t* regex,char* content){regmatch_t matches[regex->re_nsub + 1];errno_t state = regexec(regex,content,regex->re_nsub + 1,matches,0);if(state == REG_NOMATCH){_r_release();return NULL;}char* reval = (char*)calloc(matches[0].rm_eo - matches[0].rm_so + 1,sizeof(char));memcpy(reval,content + position + matches[0].rm_so,matches[0].rm_eo - matches[0].rm_so);position += matches[0].rm_eo;return reval;
}//replace first
bool regreplace(regex_t* regex,char** content,char* replacement){regmatch_t matches[regex->re_nsub + 1];errno_t state = regexec(regex,*content,regex->re_nsub + 1,matches,0);if(state == REG_NOMATCH){return false;}char* newContent = (char*)calloc(strlen(*content) + strlen(replacement) - (matches[0].rm_eo - matches[0].rm_so),sizeof(char));size_t head = matches[0].rm_so;size_t middle = strlen(replacement);size_t end = strlen(*content) - matches[0].rm_eo;memcpy(newContent,*content,head);memcpy(newContent + head,replacement,middle);memcpy(newContent + head + middle,*content + matches[0].rm_eo,end);*content = newContent;return true;
}//replace all
void regreplaceAll(regex_t* regex,char** content,char* replacement){for(;regreplace(regex,content,replacement););
}void _r_release(void){position = 0;
}#endif