CODEWITHSUNDEEP
pythonc++regexc++11
ArkaMondal
ArkaMondal

Reputation: 35

Regular Expressions are not match in c++?

I have a problem in regular expression. I have a string and the string is validate with a regular expression and it is working with the python script but not in working in c++.

Working python code:

import re
txt = "\x01msvc-server\x1Cmsvc-xyzy4\x02<?xml version=\"1.0\" encoding=\"UTF-8\"?><SVCMessage currency=\"INR\" hostName=\"msvc-xyz4\" language=\"US-en\" retransmit=\"N\" sequence=\"00\" timeout=\"90\" version=\"8\"><Amount>0.01</Amount><BusinessDate>20190506</BusinessDate><CheckNumber>0</CheckNumber><LocalDate>20170506</LocalDate><LocalTime>160722</LocalTime><RequestCode>POINT_REDEMPTION</RequestCode><RevenueCenter>0</RevenueCenter><TerminalID>21</TerminalID><TraceID>190506860722N000000</TraceID><Track2>1161111112</Track2><TransactionEmployee>0</TransactionEmployee></SVCMessage>\x03\x04"
matcher = re.compile(r".*\x01([A-Za-z0-9_-]*)\x1C([A-Za-z0-9_-]*)\x02([^\x00-\x1F\x7F]*)\x03\x04.*")
results = matcher.match(txt)

if results == None:
    print ('Invalid query , closed')
else:
    print ('sucess')

My c++ code:

#include <iostream>
#include <regex>
using namespace std;

int main()
{
    string a = "\x01msvc-server\x1Cmsvc-xyzy4\x02<?xml version=\"1.0\" encoding=\"UTF-8\"?><SVCMessage currency=\"INR\" hostName=\"msvc-xyz4\" language=\"US-en\" retransmit=\"N\" sequence=\"00\" timeout=\"90\" version=\"8\"><Amount>0.01</Amount><BusinessDate>20190506</BusinessDate><CheckNumber>0</CheckNumber><LocalDate>20170506</LocalDate><LocalTime>160722</LocalTime><RequestCode>POINT_REDEMPTION</RequestCode><RevenueCenter>0</RevenueCenter><TerminalID>21</TerminalID><TraceID>190506860722N000000</TraceID><Track2>1161111112</Track2><TransactionEmployee>0</TransactionEmployee></SVCMessage>\x03\x04";
    // Here b is object of regex- Regular Expression
    regex b(".*\x01([A-Za-z0-9_-]*)\x1C([A-Za-z0-9_-]*)\x02([^\x00-\x1F\x7F]*)\x03\x04.*");
    cout<< a << endl;


    if( regex_match(a, b)){
        cout << "String is matches Reguler Expreation " << endl;

    }else{
        cout << "String are not match" << endl;
    }

    return 0;
}

And the expected the result is - String is match ... in c++

Upvotes: 1

Views: 132

Answers (2)

sklott
sklott

Reputation: 2849

Most probably problem is in \x00 char which terminates regex string.

You initialize b using string literal which invokes explicit basic_regex( const CharT* s, flag_type f = std::regex_constants::ECMAScript ); overload.

To avoid this issue you can try to initialize it using std::string, which in turn can be initialized something like that:

char re[] = ".*\x01([A-Za-z0-9_-]*)\x1C([A-Za-z0-9_-]*)\x02([^\x00-\x1F\x7F]*)\x03\x04.*";
std::string re_str(re, sizeof(re));

Upvotes: 0

max66
max66

Reputation: 66210

What about doubling the \ in the regular expression string?

//.........VV...................VV...................VV......VV.........VV......VV...VV
regex b(".*\\x01([A-Za-z0-9-_]*)\\x1C([A-Za-z0-9-_]*)\\x02([^\\x00-\\x1F\\x7F]*)\\x03\\x04.*");

Otherwise you can use a raw literal string

// .....VVV...........................................................................VV
regex b(R"(.*\x01([A-Za-z0-9-_]*)\x1C([A-Za-z0-9-_]*)\x02([^\x00-\x1F\x7F]*)\x03\x04.*)");

Off Topic Unrequested Suggestion: avoid using namespace std; and explicit std using std::cout, std::string, std::regex, etc.

Upvotes: 1

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