&& — Logical AND operator.
Arithmetic operators perform operations of change-sign (negate), don't-change-sign, logical AND logical OR, add, subtract, multiply and divide. Note that a value or an expression may fall between two of these operators, either of which could take it as its left or right argument, as in
a + b * c.
In such cases three rules apply:
1. * and / bind to their neighbors more strongly than + and −. Thus the above expression is taken as
a + (b * c)
with * taking b and c and then + taking a and b * c.
2. + and − bind more strongly than &&, which in turn is stronger than ||:
a && b - c || d
is taken as
(a && (b - c)) || d
3. When both operators bind equally strongly, the operations are done left to right:
a - b - c
is taken as
(a - b) - c
Parentheses may be used as above to force particular groupings.