std::malloc

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

 

Utilities library

Type support (basic types, RTTI, type traits)

Dynamic memory management

Error handling

Program utilities

Variadic functions

Date and time

Function objects

initializer_list (C++11)

bitset

hash (C++11)

Relational operators

rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=

Pairs and tuples

pair

tuple (C++11)

piecewise_construct_t (C++11)

piecewise_construct (C++11)

Swap, forward and move

swap

forward (C++11)

move (C++11)

move_if_noexcept (C++11)

declval (C++11)

 

Dynamic memory management

Smart pointers
unique_ptr (C++11)
shared_ptr (C++11)
weak_ptr (C++11)
auto_ptr (deprecated)
owner_less (C++11)
enable_shared_from_this (C++11)
bad_weak_ptr (C++11)
default_delete (C++11)
Allocators
allocator
allocator_traits (C++11)
allocator_arg_t (C++11)
allocator_arg (C++11)
uses_allocator (C++11)
scoped_allocator_adaptor (C++11)
Uninitialized storage
uninitialized_copy
uninitialized_copy_n (C++11)
uninitialized_fill
uninitialized_fill_n
raw_storage_iterator
get_temporary_buffer
return_temporary_buffer
Garbage collection support
declare_reachable (C++11)
undeclare_reachable (C++11)
declare_no_pointers (C++11)
undeclare_no_pointers (C++11)
pointer_safety (C++11)
get_pointer_safety (C++11)
Miscellaneous
pointer_traits (C++11)
addressof (C++11)
align (C++11)
C Library
malloc calloc	realloc free
Low level memory management

 

Defined in header <cstdlib>
void* malloc( std::size_t size );

Allocates size bytes of uninitialized storage.

If allocation succeeds, returns a pointer to the lowest (first) byte in the allocated memory block that is suitably aligned for any scalar type.

If size is zero, the behavior is implementation defined (null pointer may be returned, or some non-null pointer may be returned that may not be used to access storage)

Parameters

size

-

number of bytes to allocate

Return value

Pointer to the beginning of newly allocated memory or null pointer if error has occurred. The pointer must be deallocated with std::free().

Notes

This function does not call constructors or initialize memory in any way. Thus preferred method of memory allocation is new expression.

Example

Run this code

#include <cstdlib>
#include <iostream>
 
int main()
{
    // Allocate an array of 4 integers
    int *array = static_cast<int *>(std::malloc(4 * sizeof(int)));
 
    if (array != nullptr) {
        for (int arrayIdx = 0; arrayIdx < 4; ++arrayIdx) {
            array[arrayIdx] = 2 * ( arrayIdx + 1 );
        }
 
        for (int arrayIdx = 0; arrayIdx < 4; ++arrayIdx) {
            std::cout << "Array item " << ( arrayIdx + 1 ) << " = " << array[arrayIdx] << '\n';
        }
        std::free(array);
    }
}

Possible output:

Array item 1 = 2
Array item 2 = 4
Array item 3 = 6
Array item 4 = 8

See also

operator newoperator new[]	allocation functions (function)
get_temporary_buffer	obtains uninitialized storage (function template)
C documentation for malloc