.append()

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MikeTython
Published Jun 23, 2025
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In C++, .append() is a method that concatenates new characters to the end of an existing string without requiring reassignment. It can be used to combine two different strings, append a portion of a string (also known as a substring), or add specific characters to the end of a string.

Syntax

str.append(str2);               // Appends entire string
str.append(str2, pos, len);     // Appends substring from str2
str.append(n, char);            // Appends character 'char' n times
str.append(first, last);        // Appends range using iterators

Parameters:

  • str2: The string to append or extract a substring from.
  • pos: The starting index in str2 (used when appending a substring).
  • len: The number of characters to append from str2, starting at pos.
  • n: The number of times to append the character char.
  • char: A character to be appended multiple times.
  • first, last: Iterators defining a range of characters to append.

Return value:

Returns a reference to the modified string (*this), allowing method chaining.

Example 1: Appending Two Strings Together

This example takes two separate strings and concatenates them:

#include <iostream>
#include <string>
using namespace std;


int main () {
  string stringOne = "Hello ";
  string stringTwo = "World!";


  //Appends stringTwo to the end of stringOne
  stringOne.append(stringTwo);


  cout << stringOne;
  return 0;
}

The output produced by this code is:

Hello World!

Example 2: Appending One Piece of a String to Another

This example takes a portion of one string and adds it to the end of another string:

#include <iostream>
#include <string>
using namespace std;


int main() {
  string str1("Straw Hat ");
  string str2("Monkey D. Luffy");


  // Appends 5 characters from index 10 of str2 to str1
  str1.append(str2, 10, 5);


  cout << str1;
  return 0;
}

The output produced by this code is:

Straw Hat Luffy

Codebyte Example: Appending Multiple Characters to a String

This codebyte example takes a specific character and adds it a specific amount of times to the end of a string:

Code
Output
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