C++ Strings

Strings in C++ are sequences of characters represented by the std::string class. They are used to store and manipulate text or sequences of characters.

1. Initializing Strings

You can initialize strings using various methods:

• Direct initialization
• Using string literals
• Concatenation

Example:

#include <iostream>
#include <string>

int main() {
    std::string greeting = "Hello, "; // Direct initialization
    std::string name = "Alice";
    std::string message = greeting + name + "!"; // Concatenation

    std::cout << message << std::endl;

    return 0;
}

2. String Operations

C++ provides various operations to manipulate strings:

• length(): Returns the length of the string.
• append(): Appends a string to the end of another string.
• substr(): Extracts a substring.
• find(): Finds the first occurrence of a substring.
• compare(): Compares two strings.

Example:

#include <iostream>
#include <string>

int main() {
    std::string sentence = "Programming in C++ is fun!";
    std::cout << "Length of the string: " << sentence.length() << std::endl;

    std::string part1 = "Hello, ";
    std::string part2 = "World!";
    part1.append(part2); // Append part2 to part1
    std::cout << part1 << std::endl;

    std::string sub = sentence.substr(14, 4); // Extract "C++"
    std::cout << "Substring: " << sub << std::endl;

    std::string searchStr = "C++";
    size_t found = sentence.find(searchStr); // Find position of "C++"
    if (found != std::string::npos) {
        std::cout << "Found '" << searchStr << "' at position " << found << std::endl;
    }

    std::string str1 = "apple";
    std::string str2 = "banana";
    int comparison = str1.compare(str2); // Compare str1 and str2
    if (comparison == 0) {
        std::cout << str1 << " is equal to " << str2 << std::endl;
    } else if (comparison < 0) {
        std::cout << str1 << " is less than " << str2 << std::endl;
    } else {
        std::cout << str1 << " is greater than " << str2 << std::endl;
    }

    return 0;
}

3. Input and Output of Strings

Strings can be input from and output to the console using std::cin and std::cout:

#include <iostream>
#include <string>

int main() {
    std::string name;

    std::cout << "Enter your name: ";
    std::getline(std::cin, name); // Read a line of input

    std::cout << "Hello, " << name << "!" << std::endl;

    return 0;
}

Conclusion

Understanding how to work with strings in C++ is essential for handling textual data effectively in programs. This chapter covered initializing strings, basic operations such as length, append, substr, find, and compare, as well as input and output operations with strings. Mastery of these concepts will enable you to manipulate and process strings in your C++ programs efficiently.