How to use the replace_copy_if() function in C++
The replace_copy_if() function is available in the algorithm library in C++.
The replace_copy_if() function is used to copy the elements by replacing the specified elements which meet a particular condition.
Syntax
Iterator replace_copy_if (First, Last, Result, Predicate, NewValue);
Parameter
The replace_copy_if() method takes the following parameters:
First: Forward iterator for the initial position of the derived range.Last: Forward iterator for the final position of the derived range.Result: An iterator pointing to the first element of the range, where the elements which met the condition have been stored.Predicate: The unary predicate function that must be satisfied for the element to be replaced.NewValue: Replacement value.
Return
The replace_copy_if() function returns the position after the last copied element in the result vector.
Code
Let’s see the code snippet.
#include <iostream>#include <algorithm>#include <vector>#include <iterator>using namespace std;bool isEVEN(int x){if (x % 2 == 0)return 1;elsereturn 0;}int main(){int arr[] = { 10, 11, 12, 13, 14, 15, 100, 200, 300 };vector<int> v(6);replace_copy_if(arr + 0, arr + 6, v.begin(), isEVEN, -9);cout<<"Result vector: "<<endl;for (int x : v)cout << x << " ";cout << endl;return 0;}
Explanation
- In lines 1 to 3, we import the required header files.
- In lines 8 to 14, we define a function which checks if a number is even.
- In line 16, we make a
mainfunction. - In line 18, we initialize an array of
inttype. - In line 19, we declare a vector of
inttype where the result will be stored. - In line 21, we use the
replace_copy_if()function to replace all the even numbers with value = -9 using the defined function at line 8. - In lines 24 to 26, we display an array and the transformed vector.
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