Editing C dynamic memory allocation (section)

==Allocation size limits==
The largest possible memory block <code>malloc</code> can allocate depends on the host system, particularly the size of physical memory and the operating system implementation.

Theoretically, the largest number should be the maximum value that can be held in a <code>[[size_t]]</code> type, which is an implementation-dependent unsigned integer representing the size of an area of memory. In the [[C99]] standard and later, it is available as the <code>SIZE_MAX</code> constant from <code>&lt;[[stdint.h]]&gt;</code>. Although not guaranteed by {{nowrap|ISO C}}, it is usually <code>2^(CHAR_BIT * [[sizeof]](size_t)) - 1</code>.

On glibc systems, the largest possible memory block <code>malloc</code> can allocate is only half this size, namely <code>2^(CHAR_BIT * [[sizeof]](ptrdiff_t) - 1) - 1</code>.<ref>{{cite web |url=https://sourceware.org/bugzilla/show_bug.cgi?id=23741#c2 |title=malloc: make malloc fail with requests larger than PTRDIFF_MAX |date=18 April 2019 |website=Sourceware Bugzilla |access-date=30 July 2020}}</ref>