std::free
| Defined in header <cstdlib>
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| void free( void* ptr ); |
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Deallocates the space previously allocated by std::malloc(), std::calloc() or std::realloc().
If ptr is a null pointer, the function does nothing.
The behavior is undefined if the value of ptr does not equal a value returned earlier by std::malloc(), std::calloc(), or std::realloc().
The behavior is undefined if the memory area referred to by ptr has already been deallocated, that is, std::free() or std::realloc() has already been called with ptr as the argument and no calls to std::malloc(), std::calloc() or std::realloc() resulted in a pointer equal to ptr afterwards.
The behavior is undefined if after std::free() returns, an access is made through the pointer ptr (unless another allocation function happened to result in a pointer value equal to ptr)
Contents |
[edit] Parameters
| ptr | - | pointer to the memory to deallocate |
[edit] Return value
(none)
[edit] Notes
The function accepts (and does nothing with) the null pointer to reduce the amount of special-casing. Whether allocation succeeds or not, the pointer returned by an allocation function can be passed to free()
[edit] Example
#include <cstdlib> int main() { int* p1 = (int*)std::malloc(10*sizeof *p1); std::free(p1); // every allocated pointer must be freed int* p2 = (int*)std::calloc(10, sizeof *p2); int* p3 = (int*)std::realloc(p2, 1000*sizeof *p3); if(p3) // p3 not null means p2 was freed by std::realloc std::free(p3); else // p3 null means p2 was not freed std::free(p2); }
[edit] See also
| C documentation for free
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