std::string C++

In C++, the std::string class is a part of the C++ Standard Library (STL) and provides a convenient way to work with strings. It is a dynamic array of characters that automatically manages memory and provides various member functions to manipulate and access strings efficiently. Unlike C-style strings, std::string objects can grow or shrink dynamically as needed, making them more flexible and less prone to buffer overflows.

Here’s an explanation of some important functions of the std::string class along with examples:

Table of Contents

Declaration and Initialization:

You can declare and initialize an std::string in different ways:

   #include <iostream>
   #include <string>

   int main() {
       std::string str1;                      // Empty string
       std::string str2 = "Hello, World!";    // Initialization with a C-string
       std::string str3("Welcome to C++");    // Initialization with a C-string using constructor
       std::string str4 = str2;               // Copy constructor

       std::cout << "str2: " << str2 << std::endl;
       std::cout << "str3: " << str3 << std::endl;
       std::cout << "str4: " << str4 << std::endl;

       return 0;
   }

Length of the String:

The length() or size() member function is used to get the length of the string.

   #include <iostream>
   #include <string>

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

Concatenation:

Strings can be concatenated using the + operator or the append() member function.

   #include <iostream>
   #include <string>

   int main() {
       std::string str1 = "Hello, ";
       std::string str2 = "World!";
       std::string result = str1 + str2; // Concatenation using operator
       // std::string result = str1.append(str2); // Concatenation using append()

       std::cout << "Concatenated string: " << result << std::endl;
       return 0;
   }

Substrings:

The substr() member function is used to extract a substring from a string.

   #include <iostream>
   #include <string>

   int main() {
       std::string str = "Hello, World!";
       std::string sub = str.substr(7, 5); // Extract "World" starting from index 7, with length 5

       std::cout << "Substring: " << sub << std::endl;
       return 0;
   }

Searching:

The find() member function is used to search for a substring within a string.

   #include <iostream>
   #include <string>

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

       if (found != std::string::npos) {
           std::cout << "Substring found at index: " << found << std::endl;
       } else {
           std::cout << "Substring not found." << std::endl;
       }
       return 0;
   }

Character Access:

Individual characters in the string can be accessed using the [] operator.

   #include <iostream>
   #include <string>

   int main() {
       std::string str = "Hello";
       char ch = str[1]; // Accessing the character at index 1 (e.g., 'e')

       std::cout << "Character at index 1: " << ch << std::endl;
       return 0;
   }

Input and Output:

std::string can be easily input and output using standard streams.

   #include <iostream>
   #include <string>

   int main() {
       std::string name;
       std::cout << "Enter your name: ";
       std::getline(std::cin, name);

       std::cout << "Hello, " << name << "!" << std::endl;
       return 0;
   }

The std::string class provides many other useful member functions like erase(), replace(), compare(), etc., which offer extensive functionality for string manipulation and handling. Using std::string is recommended in C++ as it is safer, more flexible, and provides a wide range of features to work efficiently with strings.