How to resize array in C++?

I need to do the equivalent of the following C# code in C++

Array.Resize(ref A, A.Length - 1);

How to achieve this in C++?

1

5 Answers

You cannot resize array, you can only allocate new one (with a bigger size) and copy old array's contents. If you don't want to use std::vector (for some reason) here is the code to it:

int size = 10;
int* arr = new int[size];
void resize() { size_t newSize = size * 2; int* newArr = new int[newSize]; memcpy( newArr, arr, size * sizeof(int) ); size = newSize; delete [] arr; arr = newArr;
}

code is from here .

9

The size of an array is static in C++. You cannot dynamically resize it. That's what std::vector is for:

std::vector<int> v; // size of the vector starts at 0
v.push_back(10); // v now has 1 element
v.push_back(20); // v now has 2 elements
v.push_back(30); // v now has 3 elements
v.pop_back(); // removes the 30 and resizes v to 2
v.resize(v.size() - 1); // resizes v to 1

3

1. Use std::vectoror
2. Write your own method. Allocate chunk of memory using new. with that memory you can expand till the limit of memory chunk.

Raw arrays aren't resizable in C++.

You should be using something like a Vector class which does allow resizing..

std::vector allows you to resize it as well as allowing dynamic resizing when you add elements (often making the manual resizing unnecessary for adding).

You cannot do that, see this question's answers. You may use std:vector instead.

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