Part 06 - Operators

Added by Cameron Kenneth Knight, last edited by Cameron Kenneth Knight on Sep 10, 2005  (view change)

Part 06 - Operators

Mathematical

Name Syntax example Comments
Multiplication a * b
Division a / b
Remainder a % b Often called mod or modulus
Addition a + b
Subtraction a - b
Exponent a ** b Do not confuse this with Bitwise Xor ^
Bitshift Right a >> b
Bitshift Left a << b
Bitwise And a & b
Bitwise Or a | b
Bitwise Xor a ^ b

The mathematical operators can also be used in the syntax a <operator>= b, for example, a += b.
This is merely a shortcut for a = a <operator> b, or in our example a = a + b.

Relational and Logical

Name Syntax Example Comments
Less Than a < b
Greater Than a > b
Less Than or Equal To a <= b
Greater Than or Equal To a >= b
Equality a == b
Inequality a != b
Logical And a and b Only use when a and b are boolean values
Logical Or a or b Only use when a and b are boolean values
Logical Not not a Only use when a is a boolean value

Types

Name Syntax Example Comments
Typecast cast(string, a)
Typecast a as string
Type Equality/Compatibility a isa string
Type Retrieval typeof(string)
Type Retrieval a.GetType()

Primary

Name Syntax Example Comments
Member A.B Classes are described in Part 08 - Classes
Function Call f(x) Functions are described in Part 07 - Functions
Post Increment i++ See Difference between Pre and Post Increment/Decrement
Post Decrement i-- See Difference between Pre and Post Increment/Decrement
Constructor Call o = MyClass() Classes are described in Part 08 - Classes

Unary

Name Syntax Example Comments
Negative Value -5
Pre Increment ++i See Difference between Pre and Post Increment/Decrement
Pre Decrement --i See Difference between Pre and Post Increment/Decrement
Grouping (a + b)

Difference between Pre and Post Increment/Decrement

When writing inline code, Pre Increment/Decrement (++i/--i) commit the action, then return its new value, whereas Post Increment/Decrement (i++/i--) return the current value, then commit the change.

preincrement vs. postincrement
num = 0
for i in range(5):
    print num++
print '---'
num = 0
for i in range(5):
    print ++num
Output
0
1
2
3
4
---
1
2
3
4
5
Recommendation

To make your code more readable, avoid using the incrementors and decrementors.
Instead, use i += 1 and i -= 1.

Exercises

  1. Put your hands on a wall, move your left foot back about 3 feet, move the right foot back 2 feet.

Go on to Part 07 - Functions

Labels

 
(None)