C++ POSIX正则表达式不匹配
这是我第一次尝试POSIX正则表达式。我尝试了以下代码,但没有得到预期的结果。我需要从字符串中单独获取数字。我在LinuxMint上运行代码,使用g++4.7.2编译C++ POSIX正则表达式不匹配,c++,regex,C++,Regex,这是我第一次尝试POSIX正则表达式。我尝试了以下代码,但没有得到预期的结果。我需要从字符串中单独获取数字。我在LinuxMint上运行代码,使用g++4.7.2编译 #include <stdio.h> #include <strings.h> #include <regex.h> int main() { int ret; char string[512] = "Odd:97531|Even:86420"; regex_t pat
#include <stdio.h>
#include <strings.h>
#include <regex.h>
int main()
{
int ret;
char string[512] = "Odd:97531|Even:86420";
regex_t pattern;
ret = regcomp(&pattern, "[0-9]*", REG_EXTENDED);
if(ret < 0)
{
char err[512] = {};
regerror(ret, &pattern, err, 500);
printf("Regex compile error : %s\n", err);
return -1;
}
else
{
printf("Number of subexpression : %d\n", pattern.re_nsub);
}
int nmatch = 5;
regmatch_t match[5];
ret = regexec(&pattern, string, nmatch, match, 0);
if(ret < 0)
{
char err[512] = {};
regerror(ret, &pattern, err, 500);
printf("Regex execute error : %s\n", err);
return -2;
}
else
{
printf("Number of subexpression : %d\n", pattern.re_nsub);
for(int I = 0; I < nmatch; I++)
printf("Match %02d : %.*s (%d to %d)\n", I + 1,
match[I].rm_eo - match[I].rm_so, string + match[I].rm_so,
match[I].rm_so, match[I].rm_eo);
}
return 0;
}
我做错了什么?有人在这方面帮助我。
[0-9]*
匹配零或更多十进制数字。显然,字符串的开头是匹配的。您可能需要[0-9]+
,它代表一个或多个十进制数字
此外,要多次匹配同一模式,需要使用不同的偏移量多次调用regexec()nmatch
用于正则表达式中的不同括号,而不是用于匹配多个匹配项
完整的优化代码如下所示:
int main()
{
int ret;
char string[512] = "Odd:97531|Even:86420";
regex_t pattern;
ret = regcomp(&pattern, "[0-9]+", REG_EXTENDED);
if(ret != 0)
{
char err[512] = {};
regerror(ret, &pattern, err, 500);
printf("Regex compile error : %s\n", err);
return -1;
}
else
{
printf("Number of subexpression : %d\n", pattern.re_nsub);
}
regmatch_t match;
char *notmatched = string;
for (int I = 1; regexec(&pattern, notmatched, 1, &match, 0) == 0; ++I) {
printf("Match %02d : %.*s (%d to %d)\n", I,
match.rm_eo - match.rm_so, notmatched + match.rm_so,
match.rm_so, match.rm_eo);
notmatched += match.rm_eo;
}
return 0;
}
正则表达式直到GCC4.9才开始工作,请使用boost::Regex@Kiroxas,因为它与C++11中的正则表达式无关。关于POSIX正则表达式。如果您使用POSIX正则表达式库和C++,我编写了一个C++封装器,它将细节抽象出来,使其与Python的RE模块非常相似:
int main()
{
int ret;
char string[512] = "Odd:97531|Even:86420";
regex_t pattern;
ret = regcomp(&pattern, "[0-9]+", REG_EXTENDED);
if(ret != 0)
{
char err[512] = {};
regerror(ret, &pattern, err, 500);
printf("Regex compile error : %s\n", err);
return -1;
}
else
{
printf("Number of subexpression : %d\n", pattern.re_nsub);
}
regmatch_t match;
char *notmatched = string;
for (int I = 1; regexec(&pattern, notmatched, 1, &match, 0) == 0; ++I) {
printf("Match %02d : %.*s (%d to %d)\n", I,
match.rm_eo - match.rm_so, notmatched + match.rm_so,
match.rm_so, match.rm_eo);
notmatched += match.rm_eo;
}
return 0;
}