How to reduce array after delete element C++

Question

i try to reduce the length of an array after delete element i have try array:

int* arr = new int[5];
    for (int i = 0; i < 5; i++) {
        arr[i] = i;
}

and the function:

void del1(int* arr, int n) {
    int pos = 0;
    for (int i = 0; i < n; i++) {
        if (arr[i] == 3) {
            pos = i;
        }
    }
    for (int i = pos; i < n - 1; i++) {
        arr[i] = arr[i + 1];
    }
    arr[n - 1] = 0;

    for (int i = 0; i < n; i++) {
        cout << arr[i] << " ";
    }
}

is there a way to reduce the length of the array that sent to the function?

What does "reduce the length of the array that sent to the function" mean? Please be specific. — Sam Varshavchik
– Sam Varshavchik, Commented Feb 26, 2023 at 15:49
Have you ever looked at std::vector? C++'s resizable array? In any case stop using "C" style arrays as you are doing now and have a look at the C++ core guidelines regarding new/delete. New/delete hardly ever need to be used unless you are writing your own datastructures. — Pepijn Kramer
– Pepijn Kramer, Commented Feb 26, 2023 at 15:52
Do you mean reduce the size of your array that's passed as a parameter to del1 function? — CPPUIX
– CPPUIX, Commented Feb 26, 2023 at 15:53
by reduce the length i mean at the beginning the length is 5, and after using te function the length will be 4 — Ido Divon
– Ido Divon, Commented Feb 26, 2023 at 16:01
does this answer your question? [stackoverflow.com/questions/3749660/how-to-resize-array-in-c] — CPPUIX
– CPPUIX, Commented Feb 26, 2023 at 16:04

Pepijn Kramer · Accepted Answer · 2023-02-26 16:06:17Z

0

What you are looking for is expressed like this in C++ : (online demo : https://onlinegdb.com/OiDJg4849)

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

int main()
{
    std::vector<int> values{ 1,2,3,4,5 };

    // remove/erase idiom 
    // https://en.cppreference.com/w/cpp/algorithm/remove
    // the last argument is a lambda expression
    // https://en.cppreference.com/w/cpp/language/lambda

    auto it = std::remove(values.begin(), values.end(), 3);
    values.erase(it, values.end());

    //https://en.cppreference.com/w/cpp/language/range-for
    for (const auto& value : values)
    {
        std::cout << value << "\n";
    }

    return 0;
}

edited Feb 26, 2023 at 16:06

answered Feb 26, 2023 at 16:00

Pepijn Kramer

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