How to Remove Element from Vector in C++: Syntax and Examples

To remove an element from a std::vector in C++, use the erase() method with an iterator pointing to the element. For removing by value, combine std::remove() with erase() to delete all matching elements efficiently.

Syntax

The erase() method removes elements from a vector by position or range. The std::remove() algorithm shifts elements to remove by value but does not change vector size, so it must be combined with erase() to actually delete elements.

• vec.erase(position); removes element at position.
• vec.erase(start, end); removes elements in the range [start, end).
• vec.erase(std::remove(vec.begin(), vec.end(), value), vec.end()); removes all elements equal to value.

cpp

vec.erase(position); // Remove element at iterator position
vec.erase(start, end); // Remove elements in range [start, end)
vec.erase(std::remove(vec.begin(), vec.end(), value), vec.end()); // Remove all elements equal to value

Example

This example shows how to remove a single element by index and how to remove all elements with a specific value from a vector.

cpp

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

int main() {
    std::vector<int> numbers = {10, 20, 30, 20, 40, 20, 50};

    // Remove element at index 2 (value 30)
    numbers.erase(numbers.begin() + 2);

    // Remove all elements with value 20
    numbers.erase(std::remove(numbers.begin(), numbers.end(), 20), numbers.end());

    // Print remaining elements
    for (int num : numbers) {
        std::cout << num << " ";
    }
    std::cout << std::endl;

    return 0;
}

Output

10 40 50 

Common Pitfalls

One common mistake is using std::remove() alone, which only moves elements but does not reduce the vector size, leaving unwanted elements at the end. Another is erasing elements inside a loop without updating iterators, which can cause invalid access or skip elements.

Always combine std::remove() with erase() to actually remove elements by value. When erasing in loops, update the iterator properly.

cpp

#include <vector>
#include <algorithm>

// Wrong: std::remove alone does not shrink vector size
std::vector<int> v = {1, 2, 3, 2, 4};
std::remove(v.begin(), v.end(), 2); // Elements moved but size unchanged

// Correct: combine remove and erase
v.erase(std::remove(v.begin(), v.end(), 2), v.end());

Quick Reference

Operation	Code Example	Description
Remove by position	vec.erase(vec.begin() + index);	Removes element at given index.
Remove by range	vec.erase(vec.begin() + start, vec.begin() + end);	Removes elements in [start, end) range.
Remove by value	vec.erase(std::remove(vec.begin(), vec.end(), value), vec.end());	Removes all elements equal to value.
Clear all	vec.clear();	Removes all elements from vector.

Key Takeaways

Use erase() with iterators to remove elements by position or range.

Combine std::remove() with erase() to remove elements by value correctly.

Never use std::remove() alone as it does not change vector size.

When erasing elements in loops, update iterators to avoid invalid access.

Use clear() to remove all elements from a vector quickly.