Implement Your Own sizeof

Source

Here is an implementation.

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#define my_sizeof(type) (char *)(&type+1)-(char*)(&type) int main() { double x; printf("%d", my_sizeof(x)); getchar(); return 0; }

You can also implement using function instead of macro, but function implementation cannot be done in C as C doesn’t support function overloading and sizeof() is supposed to receive parameters of all data types.

Note that above implementation assumes that size of character is one byte.

Time Complexity: O(1)
Space Complexity: O(1)