C++ Strings

Creating Strings

In C++, a string is an object of the std::string class. Include <string> to use it (often available via <iostream>).

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

int main() {
    string greeting = "Hello, World!";
    cout << greeting << endl;
    cout << "Length: " << greeting.length() << endl;
    return 0;
}

Output:

Hello, World!
Length: 13

String Concatenation

Use the + operator to join strings:

string firstName = "John";
string lastName  = "Doe";
string fullName  = firstName + " " + lastName;
cout << fullName;   // John Doe

Useful String Methods

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

int main() {
    string s = "Hello, World!";
    cout << s.length()      << endl;    // 13
    cout << s.substr(7, 5)  << endl;    // World
    cout << s.find("World") << endl;    // 7

    s.replace(7, 5, "C++");
    cout << s << endl;                  // Hello, C++!
    return 0;
}

Accessing Characters

string s = "Hello";
cout << s[0];       // H
cout << s[4];       // o
cout << s.at(1);    // e  (safe, throws if out of range)

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

int main() {
    string s;
    cout << "Enter a word: ";
    cin >> s;
    cout << "Length: " << s.length() << endl;
    cout << "First: "  << s[0] << endl;
    cout << "Last: "   << s[s.length()-1] << endl;
    cout << "Reversed: ";
    for (int i = s.length()-1; i >= 0; i--) cout << s[i];
    cout << endl;
    return 0;
}

Summary

• string is a class from the <string> header.
• Concatenate with +; access characters with [i] or .at(i).
• Key methods: length(), substr(), find(), replace().