int count(mixed var);
Returns the number of elements in var, which is typically an array (since anything else will have one element).
Returns 1 if the variable is not an array.
Returns 0 if the variable is not set.
count() may return 0 for a variable that isn't set, but it may also return 0 for a variable that has been initialized with an empty array. Use isset() to test if a variable is set.