Replace Substring with Another Substring in C++

Here we will see how to replace substring with another substring. It replaces the portion of the string that begins at character pos and spans len characters.

The structure of the replace function is like below:

string& replace (size_t pos, size_t len, const string& str, size_t subpos, size_t sublen);

The parameters are pos: It is an insertion point, str : It is a string object, len : It contains information about number of characters to erase.

Algorithm

Step 1: Get the main string, and the string which will be replaced. And the match string
Step 2: While the match string is present in the main string:
Step 2.1: Replace it with the given string.
Step 3: Return the modified string

Example Code

 Live Demo

#include <iostream>
#include <string>
using namespace std;
int main () {
   string base = "this is a test string.";
   string str2 = "n example";
   string str3 = "sample phrase";
   string str4 = "useful.";
   string str = base;
   str.replace(9,5,str2);
   str.replace(19,6,str3,7,6);
   str.replace(8,10,"just a");
   str.replace(8,6,"a shorty",7);
   str.replace(22,1,3,'!');
   str.replace(str.begin(),str.end()-3,str3);
   str.replace(str.begin(),str.begin()+6,"replace");
   str.replace(str.begin()+8,str.begin()+14,"is coolness",7);
   str.replace(str.begin()+12,str.end()-4,4,'o');
   str.replace(str.begin()+11,str.end(),str4.begin(),str4.end());
   cout << str << '\n';
   return 0;
}

Output

replace is useful.