检查字符串是否可能与正则表达式匹配

Pottsiex5 发表于 Dev

Pottsiex5

基本上，我希望能够有一个正则表达式，例如＃[0-9] +并能够检查字符串是否可以匹配它。例如，如果我得到用户输入并且他们输入“＃”，则此字符串与正则表达式不匹配，但是如果用户也输入了一些数字，则可能是该字符串。

我知道C ++具有matchs（）函数，但是有什么我想要的东西吗？或采取某种方式？

谢谢

西蒙·克雷默

免责声明：以下是一种非常幼稚的方法，既不快捷也不美观。然而，它可以完成简单的正则表达式。我不建议您在不了解其用途的情况下使用它

#include <string>
#include <iostream>
#include <regex>


bool is_valid_regex_string(const std::string& rgx_str)
{
    bool bResult = true;
    try
    {
        std::regex tmp(rgx_str);
    }
    catch (const std::regex_error& e)
    {
        (e);
        bResult = false;
    }
    return bResult;
}

std::string create_partial_regex_string(const std::string& rgx_str)
{
    std::string par_rgx_str;
    for (int i = 1; i <= rgx_str.size(); i++)
    {
        std::string sub_rgx_str = rgx_str.substr(0, i);
        if (is_valid_regex_string(sub_rgx_str))
        {
            if (!par_rgx_str.empty())par_rgx_str += "|";
            par_rgx_str += "(" + sub_rgx_str + ")";
        }
    }
    //return par_rgx_str;
    return "^" + par_rgx_str + "$";
}


void testPartialRegex(const std::string& rgx, const std::string& str)
{
    std::string partialRegexString = create_partial_regex_string(rgx);
    std::regex partRegex(partialRegexString);
    std::cout << "\tTESTING \"" << str << "\" against \"" << partialRegexString << "\" :" << std::endl;

    std::smatch base_match;
    std::cout << "\t\t-> " << (std::regex_match(str, partRegex) ? "true" : "false") << std::endl;
}

void test(const std::string& str)
{
    std::cout << "\n###########################################\nTESTING \"" << str << "\"\n" << std::endl;
    for (int i = 1; i <= str.size(); i++)
    {
        testPartialRegex("#[0-9]+", str.substr(0, i));
    }
    std::cout << "\n###########################################\n" << std::endl;

}



int main()
{

    test("#123456");    
    test("#12a3456");    
    test("#b");    
    test("123456");    
    test("##");    
    return 0;
}

输出：

###########################################
TESTING "#123456"

        TESTING "#" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> true
        TESTING "#1" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> true
        TESTING "#12" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> true
        TESTING "#123" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> true
        TESTING "#1234" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> true
        TESTING "#12345" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> true
        TESTING "#123456" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> true

###########################################


###########################################
TESTING "#12a3456"

        TESTING "#" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> true
        TESTING "#1" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> true
        TESTING "#12" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> true
        TESTING "#12a" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> false
        TESTING "#12a3" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> false
        TESTING "#12a34" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> false
        TESTING "#12a345" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> false
        TESTING "#12a3456" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> false

###########################################


###########################################
TESTING "#b"

        TESTING "#" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> true
        TESTING "#b" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> false

###########################################


###########################################
TESTING "123456"

        TESTING "1" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> false
        TESTING "12" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> false
        TESTING "123" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> false
        TESTING "1234" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> false
        TESTING "12345" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> false
        TESTING "123456" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> false

###########################################


###########################################
TESTING "##"

        TESTING "#" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> true
        TESTING "##" against "^(#)|(#[0-9])|(#[0-9]+)$" :
                -> false

###########################################