KITFORMA · EDITORIAL ANSWER
Why does allocating sizeof(pointer) corrupt a larger C structure?
KitForma editorial guide. The pointer and the object it points at have different sizes. `malloc(sizeof p)` allocates room for p itself, not necessarily a complete structure.
Step-by-step answer
The pointer and the object it points at have different sizes.
malloc(sizeof p) allocates room for p itself, not necessarily a complete structure.
For one object use p = malloc(sizeof *p) after including stdlib.h, and check the returned pointer before initialization. For an array, check the element-count multiplication before allocating. In C, a cast is not needed to convert a valid void pointer result; do not use a cast to hide a missing declaration warning.
Test a structure larger than a pointer with AddressSanitizer. A successful allocation only grants raw storage: it does not initialize the fields or establish their application invariants.Sources and verification
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