How to resize array in C++?

Question

Possible Duplicate:
Can you resize a C++ array after initialization?

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++?

Answer 1

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).

Answer 2

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;

v.push_back(1);
v.push_back(2);
v.push_back(3);

v.resize(v.size()-1);

Answer 3

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

Answer 4

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 http://www.cplusplus.com/forum/general/11111/.

Answer 5

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

Answer 6

Try realloc()

int size,*a;
a = 0;
size = 3;
a = (int*) realloc(a,size*sizeof(int));
a[0] = 16;
a[1] = 24;
a[2] = -5;
size ++;
a = (int*) realloc(a,size*sizeof(int)); //Reallocates more memory to the 'array'
a[3] = 44;
free(a); //Free the memory you allocated once you are done using it.

To call realloc() remember to #include <cstdlib>