Programming Cheat Sheet

A cheat sheet in English by godley

5,214 views 2,273 downloads 4 Aug 2015 History

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Data types

name	value
string	"anything1234!@£$%"
integer	1234
float	1.2345
bool	True/False

Variable naming rules

1. Easy to remember

2. Short

3. No spaces

4. Cannot start with a number

5. Can only contain letters, numbers and underscores

Collections and generics

Name	Usage	Code
List	Multiple items in one variable	["apple", "banana", "strawberry"]
Dictionary	Multiple key-value pairs in one variable	{"hello": "world"}

Casting

cast	what it does
str()	converts to a string
int()	converts to an integer
float()	converts to a float

Casting is used to convert between values. It needs to occur before doing any mathematical calculations with an input() from a user because user input is always strings.

Variable assignment

name = "abcdef123"
age = 18
height = 3.14

Useful python functions

print("text")	outputs text to screen
input("text")	prints text and allows input from a user
round(3.14)	rounds a float down to an integer

Comparators

symbol	meaning
==	equal to
>	larger than
<	less than
>=	larger than or equal
<=	less than or equal
!=	not equal

Boolean operators

and	both values must be true
or	either value may be true
xor	either value may be true, but not both

Arithmetic operators

+	add
-	subtract
*	multiply
/	divide
**	power
%	modulus

Conditionals

value = 3
if value < 4:
        print("less than 4")
elif value > 2:
        print("larger than 2")
else:
        print("some other value")

else and elif must follow an if. Else cannot come before elif. Whitespace before the print statements indicates they are only to print if the condition is met

Loops

# infinite loop
while True:
        print("cheese!")

# counter loop - 0-9
for i in range(10):
        print(i)

# iterating a list
collection = ['apple', 'orange', 'banana']
for value in collection:
        print(value)

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