231031_TJ_CheatSheet1.md

Cheatsheet Tigerjython

Syntax

• Functions and control structures are structured using indentation of code blocks
• Comments start with a '#'
• Python is case sensitive, Name and name are two different variables.

Control Structures

Loops

repeat n:
	Block of statements

for i in range(n):
	Block of statements
	
for x in list:
	Block of statements

while condition:
	Block of statements

Conditional Statements

if condition:
	Block of Statements

if condition:
	Block of statements
else:
	Block of statements

if condition:
	Block of statements
elif condition:
	Block of statements
else:
	Block of Statements

Combine conditions (examples)

if x < 10 and x != 5:
if x == 2 or x == 5:

Functions

Definition

def name(parameter):   # parameters ony when required
	Block of statements
	return value   # the return statement and a value are optional.

Call the function

name(parameter)

Functions can have several parameters, the paranthesis are always required.

Example

def maximum(x, y):
	if x >= y:
		return x
	else:
		return y

x = 5
def f():
	global x   # a global variable can be changed inside a function if referrecd to
	x += 1

Data Types

Variables have no type and are referencing/pointing to values. Each value has a defined type.

• bool Boolean value, either True or False
• int Integer, whole number Ex. 234, 56, 0, 1
• float Decimal number Ex. 12.0 23.234 6.023e+12
• complex complex number complex(2, 3)
• str string, text with characters "Hello" 'See you'
• list mutable list of values, array [1,2,'Hi']
• tuple immutable list of values, array (1, 2, 'Hi')
• dictionary mutable key-value pairs {"Wan Chai":345, "North Point",34}

Mathematical Operations

• + - * / Basic operations
• // % Integer division, Division 6//4 -> 1, Remainder of integer division 6%4 -> 2
• ** to express exponents

Many mathematical functions are defined inside the module math, you need to import it when used.

from math import sqrt, pi
print sqrt(3)
print("Pi =", pi)

import math
print math.sqrt(3)
print("Pi =", math.pi)

Random numbers

You need to import the modul random, for example with import random

```python` random.random() # gets random float in the range 0 <= z < 1 random.randint(a, b) # gets random int in the range of a <= z <= b

## Basic operations with lists
```python
li = [2, 4, 6]
li[0]   # -> 2 first element

range(5)   # -> [0, 1, 2, 3, 4]
range(5, 8)   # -> [5, 6, 7]
range(5, 12, 3)   # -> [5, 8, 11]

len(list)   # -> returns the number of Elements of list
list.append(Element)   # -> attaches Element at the end of the list
list.index(Element)   # -> returns the location of Element in the list with its index
list.insert(index Elementl)   # -> inserts Element at the position given by index
list.remove(Element)   # -> removes Element from the list
list.sort()   # -> sort the elements of the list
x in list   # -> returns `True` if x is in the list, otherwise `False`