C++ string to int

复制

#include <iostream>

#include <string>

using namespace std;

 

// Driver Code

int main()

{

    string str = "2009, GeeksforGeeks_founded";

    string str1 = "0x6C1";

    string str2 = "-10010010101";

 

    // Calling stoi() for all strings.

    int num = stoi(str);

    int num_hex = stoi(str1, nullptr, 16);

    int num_bin = stoi(str2, nullptr, 2);

 

    // printing converted values

    cout << str << ": " << num << endl;

    cout << str1 << ": " << num_hex << endl;

    cout << str2 << ": " << num_bin << endl;

 

    return 0;

}

run~

复制

2009, GeeksforGeeks_founded: 2009

0x6C1: 1729

-10010010101: -1173

复制

#include <iostream>

#include <string>

#include <regex>

using namespace std;

 

string midstr(string oldstr, string startstr)

{

        string re = ".*?" + startstr + "(.*?)";

        regex pattern(re);

        smatch results;

        if (regex_match(oldstr, results, pattern))

                return results[1];

        else

                cout << "match failed: " << oldstr << endl;

 

}

 

 

int main()

{

        string text = "abc: 123456";

        string data;

        data = midstr(text, "abc:");

        cout << data << endl;

        int d = stoi(data.c_str());

        cout << "data:" << d << endl;

        //system("pause");

        string str = "2009, GeeksforGeeks_founded";

    string str1 = "0x6C1";

    string str2 = "-10010010101";

 

    // Calling stoi() for all strings.

    int num = stoi(str);

    int num_hex = stoi(str1, nullptr, 16);

    int num_bin = stoi(str2, nullptr, 2);

 

    // printing converted values

    cout << str << ": " << num << endl;

    cout << str1 << ": " << num_hex << endl;

    cout << str2 << ": " << num_bin << endl;

    

    string estr  = "abc12";

    try {

            num = stoi(estr);

    

    } catch (const std::invalid_argument& ex) {

        cout << "Invalid method id: " << ex.what() << endl;

    }

 

    string estr1  = "1233";

     try {

            num = stoi(estr1);

    

    } catch (const std::invalid_argument& ex) {

        cout << "Invalid method id: " << ex.what() << endl;

    }

    cout << "num:" << num << endl;

}

run~

复制

123456

data:123456

2009, GeeksforGeeks_founded: 2009

0x6C1: 1729

-10010010101: -1173

Invalid method id: stoi

num:1233