Will the 2nd conditional in an OR ever be executed if the 1st conditional passes?

For example:

if(pos == -1 || character_ar开发者_如何学Goray[pos] == 0) {

}

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

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

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C supports short-circuit evaluation with the logical || and && operators, so in your case it should work as you describe, i.e. not crash.

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This is language specific, but most languages will ignore the rest of the statement if the first part is true for a ||.

Similarly, most languages will ignore the rest of the statement if a part of a && is false.

If you want everything to be executed, then use the single | and & operators instead.

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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)