Insert Substring in C++

Inserting a substring into a specific position within a std::string is done using the insert() method. This method modifies the original string by adding the new substring at the specified position.

Basic Usage

The insert() method requires two arguments: the position to insert the substring and the substring itself. For example:

1#include <iostream>
2#include <string>
3
4int main(){
5  std::string Greeting{"Hello!"};
6  Greeting.insert(5, " World");
7  std::cout << Greeting;
8}

1Hello World!

Inserting a Character

You can also insert a single character at a specific position.

1#include <iostream>
2#include <string>
3
4int main(){
5  std::string Greeting{"Hell World!"};
6  Greeting.insert(4, "o");
7  std::cout << Greeting;
8}

1Hello World!

Inserting Multiple Characters

The insert() method can also insert multiple characters at once.

1#include <iostream>
2#include <string>
3
4int main(){
5  std::string Greeting{"Hello!"};
6  Greeting.insert(5, "!!!", 2);
7  std::cout << Greeting;
8}

1Hello!!!

Considerations

• Position Index: Ensure the position index is within the bounds of the string to avoid undefined behavior.
• Efficiency: Frequent insertions can lead to performance issues due to potential reallocations.

Advanced Usage

You can also insert a substring from another string by specifying the starting position and length.

1#include <iostream>
2#include <string>
3
4int main(){
5  std::string Greeting{"Hello "};
6  std::string Name{"Alice Wonderland"};
7
8  Greeting.insert(6, Name, 0, 5);
9  std::cout << Greeting;
10}

1Hello Alice

In summary, the insert() method is versatile and allows you to add substrings, single characters, or multiple characters to a std::string at any position you need.