Deallocates the space previously allocated bymalloc(),calloc(),aligned_alloc(),(since C11) orrealloc().

Ifptr is a null pointer, the function does nothing.

The behavior is undefined if the value ofptr does not equal a value returned earlier bymalloc(),calloc(),realloc(), oraligned_alloc()(since C11).

The behavior is undefined if the memory area referred to byptr has already been deallocated, that is,free(),free_sized(),free_aligned_sized()(since C23), orrealloc() has already been called withptr as the argument and no calls tomalloc(),calloc(),realloc(), oraligned_alloc()(since C11) resulted in a pointer equal toptr afterwards.

The behavior is undefined if afterfree() returns, an access is made through the pointerptr (unless another allocation function happened to result in a pointer value equal toptr).

[edit]Parameters

[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 tofree().

[edit]Example

#include <stdlib.h> int main(void){int*p1=malloc(10*sizeof*p1);    free(p1);// every allocated pointer must be freed int*p2=calloc(10,sizeof*p2);int*p3=realloc(p2,1000*sizeof*p3);if(p3)// p3 not null means p2 was freed by realloc       free(p3);else// p3 null means p2 was not freed       free(p2);}

[edit]References

[edit]See also

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