C++ Strings

Welcome to The Coding College! Strings are an essential part of C++ programming, allowing you to store and manipulate sequences of characters. In this tutorial, you’ll learn how to use strings in C++, including their declaration, operations, and common methods.

What Are Strings in C++?

A string is a sequence of characters enclosed in double quotes (" "). In C++, strings can be handled in two primary ways:

1. C-Style Strings: Character arrays (char[]).
2. C++ Strings: Using the std::string class from the Standard Template Library (STL).

This guide focuses on std::string, as it is more modern and versatile compared to C-style strings.

Declaring Strings in C++

Using std::string

#include <iostream>
#include <string>  // Include the string library
using namespace std;

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

Output:

Hello, World!  

String Operations

1. Assigning Strings

You can assign values to strings using the assignment operator (=).

string name = "Alice";

2. Concatenating Strings

Use the + operator or the append() method to combine strings.

string firstName = "Alice";
string lastName = "Smith";

// Using +
string fullName = firstName + " " + lastName;
cout << fullName << endl;

// Using append()
fullName = firstName.append(" ").append(lastName);
cout << fullName << endl;

Output:

Alice Smith  
Alice Smith  

3. Accessing Characters

You can access individual characters using the subscript operator ([]) or the .at() method.

Example:

string word = "Hello";
cout << word[0] << endl;      // H
cout << word.at(1) << endl;   // e

4. Modifying Characters

Strings are mutable, so you can change individual characters.

Example:

string word = "Hello";
word[0] = 'Y';
cout << word << endl;  // Yello

5. String Length

Use the .size() or .length() method to get the length of a string.

Example:

string word = "Programming";
cout << "Length: " << word.length() << endl;

Output:

Length: 11  

Common String Methods

Practical Examples

Example 1: String Input

Use getline() to read an entire string, including spaces.

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

int main() {
    string name;

    cout << "Enter your name: ";
    getline(cin, name);  // Reads the entire line
    cout << "Hello, " << name << "!" << endl;

    return 0;
}

Output:

Enter your name: John Doe  
Hello, John Doe!  

Example 2: String Manipulation

Extract and modify substrings.

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

int main() {
    string sentence = "Welcome to The Coding College!";

    // Extract substring
    string word = sentence.substr(11, 3);  // "The"
    cout << "Substring: " << word << endl;

    // Replace a word
    sentence.replace(11, 3, "Your");
    cout << "Modified Sentence: " << sentence << endl;

    return 0;
}

Output:

Substring: The  
Modified Sentence: Welcome to Your Coding College!  

Using Strings in Loops

You can iterate through strings using loops to access or manipulate characters.

Example:

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

int main() {
    string word = "Code";

    for (int i = 0; i < word.size(); i++) {
        cout << word[i] << endl;
    }

    return 0;
}

Output:

C  
o  
d  
e  

Difference Between std::string and C-Style Strings

Explore More at The Coding College

This guide introduces the basics of strings in C++. To dive deeper into topics like advanced string manipulation, regular expressions, or memory optimization, explore our C++ tutorials.

What’s Next?

• Learn about C++ arrays to handle collections of data.
• Master file handling to work with text stored in external files.