C++ .insert()

In C++, .insert() is a method used to insert characters, substrings, or ranges into a string at a specified position. Unlike .append(), which only adds content to the end, .insert() allows placing new data at any point within the string. It is commonly used in formatting output, inserting delimiters, modifying user input, or dynamically building strings during parsing and text processing tasks.

Syntax

string.insert(pos, str);
string.insert(pos, str, subpos, sublen);
string.insert(pos, n, char);
string.insert(iterator, char);
string.insert(iterator, n, char);

template<class InputIterator>
string.insert(iterator, InputIterator first, InputIterator last);

Parameters:

• pos: The index position in the string where the insertion begins.
• str: The string or character array to insert.
• subpos: The starting position in str for partial insertion.
• sublen: The number of characters to insert from str starting at subpos.
• n: The number of times the character should be inserted.
• char: The character to be inserted.
• iterator: An iterator pointing to the insertion position within the string.
• first, last: A range of iterators defining the characters to insert.

Return value:

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

Example 1: Inserting a Substring

This example demonstrates inserting part of one string into another at a specific index:

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

int main () {
  string str1 = "Hello World!";
  string str2 = "Amazing ";

  // Inserts "Amazing " at index 6 in str1
  str1.insert(6, str2);

  cout << str1;
  return 0;
}

Copy to clipboard
Copy to clipboard

The output produced by this code is:

Hello Amazing World!

Copy to clipboard
Copy to clipboard

Example 2: Inserting a Portion of a String

This example takes a portion of one string and inserts it into another string at a specific position:

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

int main() {
  string str1 = "C++ is great!";
  string str2 = "really awesome and ";

  // Inserts 8 characters starting from index 7 of str2 into str1 at position 7
  str1.insert(7, str2, 7, 8);

  cout << str1;
  return 0;
}

Copy to clipboard
Copy to clipboard

The output produced by this code is:

C++ is awesome great!

Copy to clipboard
Copy to clipboard

Codebyte Example: Inserting Multiple Characters

This codebyte demonstrates inserting multiple characters at a specific position in a string:

Visit us
Visit us
Hide code
Code
Output
Hide output
Copy to your clipboard
Copy Codebyte
Run