Question

For example:

if(pos == -1 || character_array[pos] == 0) {

}

If pos is -1, can I count on this NEVER crashing?

Same goes with AND statements in which the first conditional fails.

Answer 1

Yes, you can count on this. The relevant parts of the C standard are 6.5.13:

Unlike the bitwise binary & operator, the && operator guarantees
left-to-right evaluation; there is a sequence point after the
evaluation of the first operand. If the first operand compares equal
to 0, the second operand is not evaluated.

and 6.5.14:

Unlike the bitwise | operator, the || operator guarantees
left-to-right evaluation; there is a sequence point after the
evaluation of the first operand. If the first operand compares unequal
to 0, the second operand is not evaluated.

For example, the following is idiomatic C:

if (foo && foo->bar > 10)