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How to use the replace_if() function in C++
Vinisha Maheshwari
In this shot, we will learn how to use the replace_if() function, which is available in the algorithm library in C++.
The replace_if() function is used to assign new value to all the elements in the range [first, last), for which pred predicate returns true.
Parameter
The replace_if() method takes the below mentioned parameter:
- First: Forward iterator for the initial position of the derived range.
- Last: Forward iterator for the final position of the derived range.
- Predicate: The unary predicate function that must be satisfied is the value of the element to be replaced.
- New value: Replacement value.
Return
The replace_if() function doesn’t return anything.
Code
Let’s see the below code snippet.
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main()
{
string s1 = "Example of replace";
cout<<"The string before replace() implementation: " <<s1<<endl;
s1.replace(6, 5, "to all", 6);
cout<<"The string after replace() implementation: "<<s1<<endl;
vector<int> v = { 134,17,20,91,46 };
replace_if(v.begin(), v.end(), [](int x) { return x % 2 == 0; }, 10);
for_each(v.begin(), v.end(),[](int x) { cout << x << ","; });
return 0;
}
Using replace_if() function in C++
Explanation
- In lines 1 to 3, we imported the required header files.
- In line 6, we made a
mainfunction. - In line 8, we initialized a string.
- In line 9, we displayed the message for the string whose characters get replaced with the original string.
- In line 10, we used the
replace()function to replace the string from the 6th index to the 10th index with the replacement string. - In line 11, we displayed the message for the replaced string along with it.
- In line 9, we initialized a vector of the
intdata type. We used thereplace_if()function to replace the multiples of 2 in the vector with 10. We displayed the vector with the replaced values.
In this way, we can use the replace_if() function in C++.
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