Using regex to parse lines into components.

regexplay.cpp

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

using namespace std;


smatch matchy(string x) { 
    smatch m;
    regex regexp("^Mem\\((\\d+)\\)=(\\d+)\n$");
    regex_search(x, m, regexp);
    return m;
}

int main() { 
    vector<string> all;
    all.push_back("Mem(100)=120\n");
    all.push_back("Mem(300)=420\n");
    all.push_back("Mem(250)=620\n");
    all.push_back("Mem(abc)=620\n");

    for (auto i : all) { 
        cout << endl << "Original: " << i;
        smatch m = matchy(i);
        if (m.size() > 2) { 
            cout << "Pattern: first=" << m[1] << "\tsecond=" << m[2] << endl;
        } else { 
            cout << "Nope, nothing." << endl;
        } 
    } 
    return 0;
}