From 4.1/2
The value contained in the object indicated by the lvalue is the rvalue result. When an lvalue-to-rvalue conversion occurs within the operand of sizeof (5.3.3) the value contained in the referenced object is not accessed, since that operator does not evaluate its operand.
Out of curiosity, I was wondering, does the same applies to the if, for, while statements, i.e lvalue is converted to rvalue when the result of statement is evaluated?
Yes. Without lvalue-to-rvalue conversion, it cannot read it's value.
Loosely speaking, think of lvalue as some sort of container, and rvalue as the value contained in the container.
C++03, section §3.10/7 reads,
Whenever an lvalue appears in a context where an rvalue is expected, the lvalue is converted to an rvalue; see 4.1, 4.2, and 4.3.
Read it along with, §4.1/2 (your quotation),
The value contained in the object indicated by the lvalue is the rvalue result.
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