Allocating Memory

In C/C++ you can use the malloc function to ask to be allocated space in memory. You pass it the size of the space you are after, and it returns a pointer to the space you can use on the heap. The following image shows the overall idea of what we are aiming to achieve.

Tip

Malloc = Memory Allocation

The following image shows the code needed to allocate space on the heap.

Malloc…

• accepts one parameter for the size of the memory to allocate in bytes.
• returns an untyped pointer to space on the heap.
• can be used with the sizeof function to make it easy to determine the size of different types.
• should have its response cast to the expected type.
• returns NULL when you are out of memory.

Tip

You can change the size of the space allocated to a pointer using realloc.

Example Code

The following example code uses malloc to create space for an integer, assigns it a value, and then free the allocation.

#include <stdlib.h>
#include "splashkit.h"

using std::to_string;

int main()
{
    // Allocate memory for an integer on the heap
    int *ptr = (int *)malloc(sizeof(int));

    // Check if memory allocation was successful
    if (ptr == NULL)
    {
        write_line("Memory allocation failed");
        return 1;
    }

    // Assign a value to the allocated memory
    *ptr = 42;

    // Print the value
    write_line("Value: " + to_string(*ptr));

    // Free the allocated memory
    free(ptr);
    ptr = NULL;

    return 0;
}