Datatype string

Data types specify whether the data are numbers (integer, double float), characters (char), strings (string), truth values (boolean), or other.
Strings consist of words, characters, digits, or a combination thereof, delimited from program code by double apostrophes.

The length of a string is the number of characters it consists of. The individual characters of a string of length n are numbered from 0 to n-1. As an alternative to strings, you could also work with arrays of characters.

Syntax

    string s;
    string str1 = "Hello World";
    string str2(10, '-');
    string str3("Hello World");

C++ String Methods

Code Example

#include <iostream>
using namespace std;

int main(){
    string str1 = "Hello";
    string str2 = "World";
    string str3 = str1 + " " + str2;

    cout << str3 << endl;
    cout << "append: " << str1.append(str2) << endl;
    cout << "length: " << str1.length() << endl;
    cout << "at: " << str1.at(3) << endl;
    cout << "insert: " << str1.insert(2, "l") << endl;

    return 0;
}

Output

Hello World
append: HelloWorld
length: 10
at: l
insert: HellloWorld

Code Explanation

1. The line #include <iostream> includes the iostream library, which provides input and output functionality in C++.
2. The line using namespace std; declares that we’re using the std namespace, which contains various standard C++ functions and objects, including cout.
3. The int main() function is the entry point of the program. It returns an integer value, typically 0, indicating successful execution.
4. Inside the main() function, three string variables are declared and initialized:
   • str1, which is initialized with the string “Hello”.
   • str2, which is initialized with the string “World”.
   • str3, which is initialized by concatenating str1, a space character, and str2.
5. The line cout << str3 << endl; uses the << operator to insert the value of str3 into the output stream, which will be displayed as “Hello World” on the console.
6. The line cout << "append: " << str1.append(str2) << endl; demonstrates the append() method of the string class. It appends str2 to str1 and inserts the result into the output stream. The output will display “append: HelloWorld”.
7. The line cout << "length: " << str1.length() << endl; demonstrates the length() method of the string class. It returns the length of str1 and inserts it into the output stream. The output will display “length: 10”.
8. The line cout << "at: " << str1.at(3) << endl; demonstrates the at() method of the string class. It accesses the character at index 3 of str1 and inserts it into the output stream. The output will display “at: l”.
9. The line cout << "insert: " << str1.insert(2, "l") << endl; demonstrates the insert() method of the string class. It inserts the string “l” at index 2 of str1 and inserts the modified string into the output stream. The output will display “insert: HellloWorld”.
10. Finally, the return 0; statement ends the main() function and returns 0 to the operating system, indicating successful program execution.