C++ Advanced Strings

In C++, strings are an essential component for working with textual data. The C++ standard library provides advanced features for manipulating strings, such as searching, modifying, and formatting. In this article, we will explore some advanced string concepts in C++ with examples.

1. Searching in Strings

The std::string class provides various methods for searching within strings. Here are some commonly used functions:

#include <iostream>
#include <string>

int main() {
    std::string str = "Hello, World!";

    // Find first occurrence of a substring
    size_t found = str.find("World");
    if (found != std::string::npos) {
        std::cout << "Substring found at position: " << found << std::endl;
    } else {
        std::cout << "Substring not found." << std::endl;
    }

    // Find last occurrence of a character
    found = str.find_last_of("l");
    if (found != std::string::npos) {
        std::cout << "Last occurrence found at position: " << found << std::endl;
    } else {
        std::cout << "Character not found." << std::endl;
    }

    // Check if a string starts with a substring
    bool startsWith = str.compare(0, 5, "Hello") == 0;
    std::cout << "Starts with 'Hello': " << std::boolalpha << startsWith << std::endl;

    // Check if a string ends with a substring
    bool endsWith = str.compare(str.length() - 6, 6, "World!") == 0;
    std::cout << "Ends with 'World!': " << std::boolalpha << endsWith << std::endl;

    return 0;
}

In the above code, we use the find() function to search for a substring within the string. If the substring is found, the function returns its position; otherwise, it returns std::string::npos. We also use the find_last_of() function to find the last occurrence of a character within the string. Additionally, we use the compare() function to check if the string starts with or ends with a specific substring.

2. Modifying Strings

The std::string class allows you to modify strings in various ways. Here are some commonly used functions:

#include <iostream>
#include <string>

int main() {
    std::string str = "Hello, World!";

    // Replace a substring
    str.replace(7, 5, "Universe");
    std::cout << "Modified string: " << str << std::endl;

    // Insert a substring
    str.insert(0, "Greeting: ");
    std::cout << "Modified string: " << str << std::endl;

    // Erase a substring
    str.erase(0, 10);
    std::cout << "Modified string: " << str << std::endl;

    // Convert to uppercase
    for (char& c : str) {
        c = std::toupper(c);
    }
    std::cout << "Modified string: " << str << std::endl;

    return 0;
}

In the above code, we use the replace() function to replace a substring within the string. We use the insert() function to insert a substring at a specified position. We use the erase() function to remove a substring from the string. Finally, we convert the string to uppercase using the toupper() function.

3. Formatting Strings

C++ provides powerful string formatting capabilities using std::stringstream or the more modern std::format. Here's an example using std::format:

#include <iostream>
#include <format>

int main() {
    std::string name = "Alice";
    int age = 25;

    std::string formattedString = std::format("My name is {} and I am {} years old.", name, age);
    std::cout << formattedString << std::endl;

    return 0;
}

In the above code, we use the std::format function to create a formatted string. We provide placeholders ({}) in the string and pass the corresponding values to the function. The function returns a formatted string with the provided values substituted.

Advanced string operations in C++ allow for powerful manipulation, searching, and formatting of strings. Utilize these features to handle complex string-related tasks effectively in your C++ programs.