Using sizeof operator on a typedef-ed struct
c++, typedef
Solution
5.3.3 Sizeof [expr.sizeof]
1) The `sizeof` operator yields the number of bytes in the object representation of its operand. The operand is either an expression, which is an unevaluated operand (Clause 5), or a parenthesized type-id. (emphasis mine)
In your case, it is a type-id so it must be parenthesized. What a type-id is is described in 8.1 Type names [dcl.name].
`sizeof tmp` should be `sizeof (tmp)`.
As in
`if (c <= sizeof tmp)` should be `if (c <= sizeof (tmp))`.
Yup, pretty "obvious and straightforward".
Problem
This might be something too obvious. However, I couldn't find the specific answer though many stackoverflow threads talk about different aspects of this. ``` typedef struct _tmp { unsigned int a; unsigned int b; } tmp; int main() { int c=10; if (c <= sizeof tmp) { printf("less\n"); } else { printf("more\n"); } return 0; } ``` I compile this prog as - ``` g++ -lstdc++ a.cpp ``` I get an error - ``` expected primary-expression before ‘)’ token ``` I think I am missing something very obvious and straightforward. But can't seem to pinpoint it :-/ Thanks!