How to Remove Element from Array based on a Condition in C++


How to Remove Element from Array based on a Condition in C++ ?

Answer

In C++, you can use STL algorithms like `remove_if` to remove elements based on a condition.



✐ Examples

1 Remove Numbers Greater Than 5

In this example,

  1. We create a vector `numbers` with elements including those to be removed based on the condition.
  2. We use the `remove_if` algorithm with a predicate to create a new vector excluding numbers greater than 5.
  3. We resize the vector to the new size after removal.

C++ Program

#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    std::vector<int> numbers = {1, 6, 2, 7, 3, 8, 4, 9, 5};
    numbers.erase(std::remove_if(numbers.begin(), numbers.end(), [](int num) { return num > 5; }), numbers.end());

    std::cout << "Vector after filtering: ";
    for (int num : numbers) {
        std::cout << num << ' ';
    }
    return 0;
}

Output

Vector after filtering: 1 2 3 4 5 

2 Remove Strings Starting with 'A'

In this example,

  1. We create a vector `words` with elements including those to be removed based on the condition.
  2. We use the `remove_if` algorithm with a predicate to create a new vector excluding strings starting with 'A'.
  3. We resize the vector to the new size after removal.

C++ Program

#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    std::vector<std::string> words = {"Apple", "Banana", "Apricot", "Grape", "Mango"};
    words.erase(std::remove_if(words.begin(), words.end(), [](const std::string& word) { return word.front() == 'A'; }), words.end());

    std::cout << "Vector after filtering: ";
    for (const std::string& word : words) {
        std::cout << word << ' ';
    }
    return 0;
}

Output

Vector after filtering: Banana Grape Mango 

Summary

In this tutorial, we learned How to Remove Element from Array based on a Condition in C++ language with well detailed examples.




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