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Religious arguments aside:
Option1:
if (pointer[i] == NULL) ... Option2:
if (!pointer[i]) ... In C is option1 functionally equivalent to option2?
Does the later resolve quicker due to absence of a comparison ?
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In C or C++, there is no special method for comparing NULL values. We can use if statements to check whether a variable is null or not.
Null is a built-in constant that has a value of zero. It is the same as the character 0 used to terminate strings in C. Null can also be the value of a pointer, which is the same as zero unless the CPU supports a special bit pattern for a null pointer.
SQL has the is [not] null predicate to test if a particular value is null . With is [not] distinct from SQL also provides a comparison operator that treats two null values as the same. Note that you have to use the negated form with not to arrive at similar logic to the equals ( = ) operator.
The value NULL does not equal zero (0), nor does it equal a space (' '). Because the NULL value cannot be equal or unequal to any value, you cannot perform any comparison on this value by using operators such as '=' or '<>'.
I prefer the explicit style (first version). It makes it obvious that there is a pointer involved and not an integer or something else but it's just a matter of style.
From a performance point of view, it should make no difference.
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