7 Expressions [expr]

7.6 Compound expressions [expr.compound]

7.6.10 Equality operators [expr.eq]

equality-expression:
	relational-expression
	equality-expression == relational-expression
	equality-expression != relational-expression
The == (equal to) and the != (not equal to) operators group left-to-right.
The lvalue-to-rvalue ([conv.lval]), array-to-pointer ([conv.array]), and function-to-pointer ([conv.func]) standard conversions are performed on the operands.
The comparison is deprecated if both operands were of array type prior to these conversions ([depr.array.comp]).
The converted operands shall have arithmetic, enumeration, pointer, or pointer-to-member type, or type std::nullptr_­t.
The operators == and != both yield true or false, i.e., a result of type bool.
In each case below, the operands shall have the same type after the specified conversions have been applied.
If at least one of the operands is a pointer, pointer conversions, function pointer conversions, and qualification conversions are performed on both operands to bring them to their composite pointer type.
Comparing pointers is defined as follows:
If at least one of the operands is a pointer to member, pointer-to-member conversions ([conv.mem]), function pointer conversions ([conv.fctptr]), and qualification conversions ([conv.qual]) are performed on both operands to bring them to their composite pointer type ([expr.type]).
Comparing pointers to members is defined as follows:
Two operands of type std::nullptr_­t or one operand of type std::nullptr_­t and the other a null pointer constant compare equal.
If two operands compare equal, the result is true for the == operator and false for the != operator.
If two operands compare unequal, the result is false for the == operator and true for the != operator.
Otherwise, the result of each of the operators is unspecified.
If both operands are of arithmetic or enumeration type, the usual arithmetic conversions are performed on both operands; each of the operators shall yield true if the specified relationship is true and false if it is false.
An object that is not an array element is considered to belong to a single-element array for this purpose; see [expr.unary.op].