How to Remove Specific Item from a Vector in C++ - Step by Step Examples

How to Remove Specific Item from a Vector in C++ ?

Answer

To remove a specific item from a vector in C++, you can use the erase method along with the std::remove algorithm.


✐ Examples

1 Remove Specific Item Using std::remove and erase

In this example,

  1. We start by including the necessary headers: <vector> and <algorithm>, and <iostream>.
  2. We create a vector named vec and initialize it with some integer values.
  3. We specify the item we want to remove and store it in a variable named item_to_remove.
  4. We use the std::remove algorithm to shift all elements that are not equal to item_to_remove to the front of the vector, and return an iterator to the new logical end of the vector.
  5. We use the erase method to remove the elements from the logical end to the actual end of the vector.
  6. Finally, we print the modified vector to standard output to see the result.

C++ Program

#include &lt;vector&gt;
#include &lt;algorithm&gt;
#include &lt;iostream&gt;

int main() {
    std::vector&lt;int&gt; vec = {10, 20, 30, 40, 50};
    int item_to_remove = 30;
    vec.erase(std::remove(vec.begin(), vec.end(), item_to_remove), vec.end());
    std::cout &lt;&lt; "Vector after removing the item " &lt;&lt; item_to_remove &lt;&lt; ": ";
    for (int val : vec) {
        std::cout &lt;&lt; val &lt;&lt; " ";
    }
    std::cout &lt;&lt; std::endl;
    return 0;
}

Output

Vector after removing the item 30: 10 20 40 50

2 Remove Specific Item Using a Custom Function

In this example,

  1. We start by including the necessary headers: <vector> and <algorithm>, and <iostream>.
  2. We define a custom function named removeItem that takes a reference to a vector and the item to remove as parameters.
  3. Inside the function, we use the std::remove algorithm to shift all elements that are not equal to the specified item to the front of the vector, and return an iterator to the new logical end of the vector.
  4. We use the erase method to remove the elements from the logical end to the actual end of the vector.
  5. We create a vector named vec and initialize it with some integer values.
  6. We specify the item we want to remove and store it in a variable named item_to_remove.
  7. We call the removeItem function, passing vec and item_to_remove as arguments.
  8. Finally, we print the modified vector to standard output to see the result.

C++ Program

#include &lt;vector&gt;
#include &lt;algorithm&gt;
#include &lt;iostream&gt;

void removeItem(std::vector&lt;int&gt; &vec, int item_to_remove) {
    vec.erase(std::remove(vec.begin(), vec.end(), item_to_remove), vec.end());
}

int main() {
    std::vector&lt;int&gt; vec = {10, 20, 30, 40, 50};
    int item_to_remove = 30;
    removeItem(vec, item_to_remove);
    std::cout &lt;&lt; "Vector after removing the item " &lt;&lt; item_to_remove &lt;&lt; ": ";
    for (int val : vec) {
        std::cout &lt;&lt; val &lt;&lt; " ";
    }
    std::cout &lt;&lt; std::endl;
    return 0;
}

Output

Vector after removing the item 30: 10 20 40 50

Summary

In this tutorial, we learned How to Remove Specific Item from a Vector in C++ language with well detailed examples.


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