What is difference between these 2 sizeof operator uses?
From here: https://github.com/openssl/openssl/commit/680e65b94c916af259bfdc2e25f1ab6e0c7a97d6?diff=split
unsigned int *pDecoded
...
memmove(pDecoded + i + 1, pDecoded + i, (written_out - i) * sizeof *pDecoded);
memmove(pDecoded + i + 1, pDecoded + i, (written_out - i) * sizeof (*pDecoded));
I think sizeof *PDecoded returns sizeof pointer to unsigned int.
Whereas, sizeof (*pDecoded) returns sizeof unsigned int.
There is no difference; these expressions are equivalent.
#include <stdio.h>
int main(void)
{
unsigned int *foo;
printf("sizeof foo <%zu> | sizeof *foo <%zu> or <%zu>\n",
sizeof foo, sizeof *foo, sizeof (*foo));
}
Output (on my machine):
sizeof foo <8> | sizeof *foo <4> or <4>
This looks like a style choice. The only other use of sizeof in the file also has superfluous parenthesis:
char a_ulabel[LABEL_BUF_SIZE + 1];
size_t a_size = sizeof(a_ulabel);
The parenthesis are only required when the operand is a type:
sizeof (int)
Otherwise, they are used to influence operator precedence.