字符串匹配——C++使用Regex

需要#include  < regex >

 

匹配

regex_match ("subject", std::regex("(sub)(.*)") //結果返回true

主要regex_match需要匹配源字符串的每個字符，這點與regex_search不同

 

查找

返回一個匹配項

    const regex pattern("(\\w+day)");
    string weekend = "Saturday and Sunday";// the source text
    smatch result;
    bool match = regex_search(weekend, result, pattern);
    if(match){
      for(size_t i = 1; i < result.size(); ++i){
 cout << result[i] << std::endl;
      }
    }

輸出結果是Saturday

 

匹配所有項

const regex pattern("(\\w+day)");
string weekend = "Saturday and Sunday, but some Fridays also.";
const sregex_token_iterator end;
for (sregex_token_iterator i(weekend.begin(),weekend.end(), pattern); i != end ; ++i){
    cout << *i << " ";
}

輸出結果是Saturday Sunday Friday

 

替換

string text = "This is a element and this a unique ID.";
const regex pattern("(\\ba (a|e|i|u|o))+");// regular expression with two capture groups
std::string replace = "an $2"; //$2表示匹配模式串的第二個字串，即以a,e,i,o,u開頭的單詞
string newtext = regex_replace(text, pattern, replace);
cout << newtext << endl;

輸出結果是This is an element and this an unique ID.