Python
From ScienceZero
Application
File Header
#!/usr/bin/python
Comments
These begin with the # character
Libraries
these go under the file header and in the format of
import libraryname
or
from libraryname import sublibraryname
Subroutines
These must be placed at the top, under the file header and library includes
def functionname(value): #do something return somevariable
Variables
There is no method to define a variable type, it is determined by the type of the first value it gets set to
a = 42 will create an int called a with value 42
Loops
Infinite
while True: #code to loop
While (check then run)
a = 0 while a < 10: a += 1
While (run then check)
while True: #code if i == 10: break #this exits the while loop
For
for i in range(127,-1,-1): #step from 127 to 0 by 1 print i
Conditionals
Equal
if i == 10: print i
Not equal
if i != 10: print i
Greater than
if i > 10: print i
Less than
if i < 10: print i
Greater than or equal to
if i >= 10: print i
Less than or equal to
if i <= 10: print i
If Else
if i == 10: print i else: print "I isn't 10"
Math
Arithmetic functions
a = b + 2 #addition a = b - 2 #subtraction a = b * 2 #multiplication a = b / 2 #division a = b % 2 #modulo division (divides b by 2, and returns the remainder)
Generating random values
import random
print random.randint(1, 5) #prints a random whole number between 1 and 5
Bitwise functions
a = b >> 2 #shift the bits of an int right by an amount of times (2 in this case) a = b << 2 #shift the bits of an int left by an amount of times (2 in this case) a = b | 2 #sets a to all the bits in b logical ORed with all the bits in 2 a = b & 2 #sets a to all the bits in b logical ANDed with all the bits in 2 a = a ^ 2 #sets a to all the bits in b logical XORed with all the bits in 2 a = ~ b #sets a to all the bits in b switched (0s become 1, 1s become 0)
Files
Writing to a text file
with open("filename.txt", "w") as outputfile1: #w for write, change to a for append to add to the bottom of an existing file outputfile1.write("Hello\r\n") #\r\n creates a new line, so whatever is written next will be on a new line outputfile1.close()
Strings
Combining strings
print "abc" + "123"