Boo Primer: [Part 06] Operators

Added by Cameron Kenneth Knight

Mathmatical

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	a cast string
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](Boo-Primer:-%5BPart-06%5D-Operators)
Pre Decrement	--i	See [Difference between Pre and Post Increment/Decrement](Boo-Primer:-%5BPart-06%5D-Operators)
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

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