Peter Ammon said:

When I add an unsigned long long and an int, what type do each of the

values get promoted to before the addition is performed? What is the

type of the resulting expression? What occurs if the addition overflows

or underflows?

Try it on your machine/compiler and let us know.

On of these days I am going to figure out what the following means.

6.3.1.8 Usual arithmetic conversions

1 Many operators that expect operands of arithmetic type cause

conversions and yield result types in a similar way. The purpose

is to determine a common real type for the operands and result.

For the specified operands, each operand is converted, without

change of type domain, to a type whose corresponding real type

is the common real type. Unless explicitly stated otherwise, the

common real type is also the corresponding real type of the result,

whose type domain is the type domain of the operands if they are

the same, and complex otherwise. This pattern is called the usual

arithmetic conversions:

First, if the corresponding real type of either operand is long

double, the other operand is converted, without change of type

domain, to a type whose corresponding real type is long double.

Otherwise, if the corresponding real type of either operand is

double, the other operand is converted, without change of type

domain, to a type whose corresponding real type is double.

Otherwise, if the corresponding real type of either operand is

float, the other operand is converted, without change of type

domain, to a type whose corresponding real type is float.

Otherwise, the integer promotions are performed on both operands.

Then the following rules are applied to the promoted operands:

If both operands have the same type, then no further

conversion is needed.

Otherwise, if both operands have signed integer types or

both have unsigned integer types, the operand with the type

of lesser integer conversion rank is converted to the type

of the operand with greater rank.

Otherwise, if the operand that has unsigned integer type has

rank greater or equal to the rank of the type of the other

operand, then the operand with signed integer type is

converted to the type of the operand with unsigned integer

type.

Otherwise, if the type of the operand with signed integer

type can represent all of the values of the type of the

operand with unsigned integer type, then the operand with

unsigned integer type is converted to the type of the

operand with signed integer type.

Otherwise, both operands are converted to the unsigned

integer type corresponding to the type of the operand

with signed integer type.