Page History

...

are not allowed because they modify the same value twice.

Non-Compliant Code Example

In this example, the order of evaluation of the operands to + is undefined.

...

As a result, programs cannot safely rely on the order of evaluatoin of operands between sequence pionts.

These examples are independend on the order of evaluation of the operands and can only be interpreted in one way.

...

Code Block
a = i + b[i+1]; ++i;

There is no ordering of subexpressions implied by the assignment operator, so the behavior of these statements is undefined.

Code Block
i = ++i + 1; a[i++] = i;

These statements are allowed by the standard.

Code Block
i = i + 1; a[i] = i;

The order of evaluation of arguments to a function is undefined.

Code Block
func(i++, i++);

This solution is appropriate when the programmer intends for both arguments to func() to be equivalent.

...

Code Block
j = i; j++; func(i, j);