Understanding String in C++ with Examples

In C++, strings are a sequence of characters or a collection of different characters represented using the std::string class. This class provides a convenient and flexible way to work with text data. To use strings in C++, you need to include the <string> header in your program.

Here are some common tasks and operations related to working with strings in C++:

1. Creating and Initializing a String:

C++ follows the OOPs concept which allows representing the string as an object of the C++ String class (std:: string). The class allows us to declare a string variable quickly, and store any sequence of characters in it. 

Here's an example that demonstrates the use of strings with the help of the string class in C++:


#include <iostream>
#include <string>

int main() {
    std::string greet = "Hello, World!";
    std::cout << greet << std::endl;
}

The output of the above code is as follows:

Hello, World!

2. Concatenating Strings:

You can concatenate strings using the + operator or the append() method. Here's an example:

#include <iostream>
#include <string>

int main() {
    // Concatenating using + operator
    std::string first_name = "John";
    std::string last_name = "Xyz";
    std::string full_name = first_name + " " + last_name;
    std::cout << "Full Name: " << full_name << std::endl;

    // Use the append method to concatenate the secondString to the end of the firstString
    std::string first_string = "Hello, ";
    std::string second_string = "World!";
    std::string full_string = first_string.append(second_string);
    std::cout << "Full String: " << full_string << std::endl;

    return 0;
}

The output of the above code is as follows:

Full Name: John Xyz
Full String: Hello, World!

3. String Length:

In C++, you can find the length of a string using the length() or size() method:

#include <iostream>
#include <string>

int main() {
    std::string first_name = "Danny";
    std::string last_name = "Xyz";
    std::cout << "First Name Length: " << first_name.size() << std::endl;
    std::cout << "Last Name Length: " << last_name.size() << std::endl;
    return 0;
}

The output of the above code is as follows:

First Name Length: 5
Last Name Length: 3

4. Accessing Individual Characters:

You can use array-like indexing to access characters of a string:

#include <iostream>
#include <string>

int main() {
    std::string word = "Programming";
    char first_char = word[0];  // Accessing the first character.
    char last_char = word[word.length()-1];  // Accessing the last character.
    std::cout << "First character: " << first_char << std::endl;
    std::cout << "Last character: " << last_char << std::endl;
    return 0;
}

The output of the above code is as follows:

First character: P
Last character: g

5. String Comparison:

In C++, you can compare two strings using the == operator. For example:

#include <iostream>
#include <string>

int main() {
    std::string str1 = "mango";
    std::string str2 = "apple";

    if (str1 == str2) {
        std::cout << "The strings are equal." << std::endl;
    } else {
        std::cout << "The strings are not equal." << std::endl;
    }

    return 0;
}

The output of the above code is as follows:

The strings are not equal.