C++ for Scientists - Technische Universität Dresden

2.3. OPERATORS 27
Operator Meaning
> greater than
>= greater than or equal to
< less than
= 1 + 7 is evaluated as if it were written 4 >= (1 + 7).
Advise
Integer values can be treated in C ++ as boolean. For the sake of clarity it is
always better to use bool for all logical expression.
This is a legacy of C where bool does not exist. Almost all techniques from C work also in
C ++— as the language name suggests — but using the new features of C ++ allows you to write
programs with better structure. For instance, if you want to store the result of a comparison
do not use an integer variable but a bool.
bool out of bound = x < min || x > max;
2.3.3 Bitwise operators
Bitwise operators allow you to test or change the bits of integers. 5 There are the following
operations:
Operator Action
& AND
| OR
ˆ exclusive OR
∼ one’s complement (NOT)
≫ shift right
≪ shift left
The shift operators bitwise shift the value on their left by the number of bits on their right:
• ≪ shifts left and adds zeros at the right end.
• ≫ shifts right and adds either 0s, if value is an unsigned type, or extends the top bit (to
preserve the sign) if it is a signed type.
5 The bitwise operators work also on bool but it is favorable to use the logical operators from the previous
section. Especially the shift operators are rather silly for bool.