关于正则表达式“(?=pattern)”型匹配,该怎么解决

关于正则表达式“(?=pattern)”型匹配
在LINUX C下使用正则"Windows (?=95|98|NT|2000)"匹配"Windows 95"中的“Windows ”不成功，为什么？  
程序运行时，regcomp返回“REG_BADRPT”，查了下手册，这样描述：
Invalid use of repetition operators such as using '*' as the first character.
也就是说，是“?”号用错了，系统把它识别成repetition operators，但网上标准的正则都是这么写的呀？难道regex.h不支持“(?=pattern)”这种匹配形式？

请各位大大们悉心指导下。

代码如下：

C/C++ code

#include<stdio.h>#include<string.h>#include<sys/types.h>#include<regex.h>/* 取子串的函数 */void substr (char *dest,char *str, unsigned start, unsigned end){  unsigned n = end - start;    printf("\n%u \n",n);  strncpy(dest, str + start, n);  dest[n] = 0;}int Pattern(char *str,char *pattern,char *result){    int cflags=REG_EXTENDED,z;    regex_t reg;    regmatch_t pm[10];    const size_t nmatch=10;    z = regcomp (&reg, pattern, cflags);    printf("%d\n",z);    if(z!=0) return z;    z = regexec (&reg, str, nmatch, pm, 0);    printf("%d\n",z);    if(z!=0) return z;    substr(result,str, pm[0].rm_so, pm[0].rm_eo);    return z;}int main(int argc, char **argv){    char result[100];    Pattern("Windows 95","Windows (?=95|98|NT|2000)",result);    printf("%s\n",result);  return 0;}

[解决办法]
在正则表达式测试器中测试了下你的正则，是对的。
但是在C中就是不对。错误提示为：Invalid preceding regular expression，大概意思是：接在Windows后的这个表达式无效吧，具体什么原因我也不太清楚，供你参考下。

C/C++ code

#include<stdio.h>#include<string.h>#include<sys/types.h>#include<regex.h>/* 取子串的函数 */void substr (char *dest,char *str, unsigned start, unsigned end){  unsigned n = end - start;  printf("[%u, %u)=%u\n", start, end, n);  strncpy(dest, str + start, n);  dest[n] = 0;}int Pattern(char *str,char *pattern,char *result){    int cflags=REG_EXTENDED, z;    regex_t reg;    regmatch_t pm[10];    const size_t nmatch=10;    char errmsg[100] = {0};    z = regcomp (&reg, pattern, cflags);    printf("1. z=%d\n",z);    if(z!=0)    {        regerror(z, &reg, errmsg, 100);        printf("1. errmsg=[%s]\n", errmsg);        return z;    }    z = regexec (&reg, str, nmatch, pm, 0);    printf("2. z=%d\n",z);    if(z!=0)    {        regerror(z, &reg, errmsg, 100);        printf("2. errmsg=[%s]\n", errmsg);        return z;    }    substr(result, str, pm[0].rm_so, pm[0].rm_eo);    return z;}int main(int argc, char **argv){    char result[100] = {0};    char pat[] = "Windows (?=95|98|NT|2000)";    int ret = Pattern("Windows 95", pat, result);    printf("ret=%d, result=[%s]\n", ret, result);    return 0;} 

 

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