How to Replace Text in a String Using Regex in C++?
Last Updated :
08 Feb, 2024
Regular expressions or what we can call regex for short are sequences of symbols and characters that create a search pattern and help us to find specific patterns within a given text. In this article, we will learn how to replace text in a string using regex in C++.
Example
Input:
str = "Hello, World! Hello, GFG!" ;
text = "Hello";
replace= "Hi";
Output:
Hi, World! Hi, GFG!
Replace Regex Matches in C++ String
To replace a text in a string using regex, we can use the function std::regex_replace(). It is defined inside the <regex> header so we need to include it in our program.
Algorithm
1. Define the main string, string to be replaced and replacement string.
2. Create a regex object of the string you want to replace.
3. Then pass the main string, regex object and replacement string to the regex_replace() function.
4. The function regex_replace() returns a new string with the replacements applied.
C++ Program to Replace Text in a String Using Regex
C++
#include <iostream>
#include <regex>
#include <string>
using namespace std;
int main()
{
string str = "Hello, World! Hello, GFG!" ;
string pattern = "Hello" ;
regex reg(pattern);
string replacement = "Hi" ;
string result = regex_replace(str, reg, replacement);
cout << "Original: " << str << endl;
cout << "Modified: " << result << endl;
return 0;
}
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Output
Original: Hello, World! Hello, GFG!
Modified: Hi, World! Hi, GFG!
Time Complexity: O(N)
Auxiliary Space: O(N)
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