C (programming language): Difference between revisions
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Memory allocated by <code>malloc</code> and <code>calloc</code> are on the heap and should be deallocated by <code>free</code> when no longer used to avoid memory leaks.<br> | Memory allocated by <code>malloc</code> and <code>calloc</code> are on the heap and should be deallocated by <code>free</code> when no longer used to avoid memory leaks.<br> | ||
Memory allocated by <code>alloca</code> is allocated on the stack and will automatically be freed. Do not call <code>free</code> on this memory. Do not allocate more than a few bytes using <code>alloca</code> or you will risk a stack overflow leading to undefined behavior.<br> | Memory allocated by <code>alloca</code> is allocated on the stack and will automatically be freed. Do not call <code>free</code> on this memory. Do not allocate more than a few bytes using <code>alloca</code> or you will risk a stack overflow leading to undefined behavior.<br> | ||
For | For automatic garbage collection, use [[C++]] which has smart pointers. | ||
Revision as of 20:22, 24 October 2019
C is the low-level programming language taught in UMD's CMSC216 class.
Usage
Memory Allocation
#include <stdlib.h>
There are 3 ways to allocate memory in C
malloc(bytes)Allocated memory is uninitialized.calloc(number, bytes)Allocated memory is initialized to 0. Allocates (number * bytes) bytes of memory.alloca(bytes)Discouraged
Memory allocated by malloc and calloc are on the heap and should be deallocated by free when no longer used to avoid memory leaks.
Memory allocated by alloca is allocated on the stack and will automatically be freed. Do not call free on this memory. Do not allocate more than a few bytes using alloca or you will risk a stack overflow leading to undefined behavior.
For automatic garbage collection, use C++ which has smart pointers.