整数匹配正则表达式模式不工作 [英] integer-matching regex pattern not working
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问题描述
我尝试检查每当输入字符串是整数时, #include< iostream>
#include< string>
#include< regex>
using namespace std;
int main()
{
string input =1;
string int_num =^ 0 $ | ^ [1-9] [0-9] * $;
regex pattern(int_num,regex_constants :: grep);
if(regex_match(input,pattern))
cout<< matched \\\
;
else
cout<< not matching\\\
;
return 0;
}
解决方案
首先,regex模式应该改为^(0 | [1-9] [0-9] *)$
,因为它看起来更好。然后,将 regex_constants :: grep
更改为 regex_constants :: ECMAScript
,或留空,因为ECMAScript是默认值。最后,需要使用 g ++ - 4.9 编译,因为g ++ - 4.8版本不能与regex lib一起使用。
I try to check whenever the input string is an integer, but nothing returns positive result with the pattern I created.
#include <iostream>
#include <string>
#include <regex>
using namespace std;
int main()
{
string input = "1";
string int_num = "^0$|^[1-9][0-9]*$";
regex pattern(int_num, regex_constants::grep);
if(regex_match(input, pattern))
cout << "matched\n";
else
cout << "not matched\n";
return 0;
}
解决方案
First of all, regex pattern should be changed to "^(0|[1-9][0-9]*)$"
because it looks better. Then, change regex_constants::grep
to regex_constants::ECMAScript
, or leave blank, because ECMAScript is default. At the end, it is required to compile with g++-4.9, because g++-4.8 version doesn't work with regex lib.
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