String Manipulation

String manipulation refers to the various operations that can be performed on strings to modify them. In C++, there are several ways to manipulate strings.

Length of a String

The length of a string can be obtained using the length() function. It returns the number of characters in the string.

Here's an example:

1std::string str = "Hello, World!";
2int length = str.length();

Accessing Characters

Individual characters in a string can be accessed using their index. The index starts at 0 for the first character and goes up to length() - 1 for the last character.

Here's an example:

1std::string str = "Hello, World!";
2char firstChar = str[0]; // Accessing the first character
3char lastChar = str[str.length() - 1]; // Accessing the last character

Substring

A substring is a portion of a larger string. The substr() function can be used to extract a substring from a string. It takes two parameters: the starting index and the length of the substring.

Here's an example:

1std::string str = "Hello, World!";
2std::string substring = str.substr(7, 5); // Extracting the substring starting from index 7 with length 5

Concatenation

Concatenation is the process of combining two or more strings into a single string. In C++, you can concatenate strings using the + operator.

Here's an example:

1std::string str1 = "Hello, ";
2std::string str2 = "World!";
3std::string concat = str1 + str2; // Concatenating str1 and str2

xxxxxxxxxx

#include <iostream>

#include <string>

​

int main() {

  std::string str = "Hello, World!";

​

  // Length of the string

  int length = str.length();

  std::cout << "Length: " << length << std::endl;

​

  // Accessing characters

  char firstChar = str[0];

  char lastChar = str[str.length() - 1];

  std::cout << "First character: " << firstChar << std::endl;

  std::cout << "Last character: " << lastChar << std::endl;

​

  // Substring

  std::string substring = str.substr(7, 5);

  std::cout << "Substring: " << substring << std::endl;

​

  // Concatenation

  std::string concat = str + " Welcome to C++!";

  std::cout << "Concatenated string: " << concat << std::endl;

​

  return 0;

}