python

python

1. print

   • () are needed after the command
   • "" quotes are used when you want to use text
   • it sends a message to output

2. variables

   • dont need to be declared
   • variable types
     • numbers
       • integers (7, -2, 43 etc)
         • name = integer (eg: int = 2)
       • float point numbers (0.2 , 7.2 etc)
         • name = float (eg: float = 7.0)
     • strings
       • name = "text" or 'text' (eg: my = "hello" )
       • strings formating
         • is used to add variables to text (eg: print "%s" % name. where name is a variable)
         • %s - strings
         • %d - integers
         • %f - floating point integers
         • %.number of digitsf - floats with fixed amount of digits
         • %x/%X - Integers in hex representation (lowercase/uppercase)
         • basic operations
           • len(string) will give the lenght of the string
           • stringname.index("o") will count how far counting from zero the 'o' occures from the start
           • stringname.count("L") will give the number of "L" in the string
           • stringname[3,7] will give a slice (counting from zero) of the string starting at 3 and ending at 7
           • stringname.upper()/lower() will convert the string to lower of upper case letters respectively
           • stringname.startswith("")/endswith("") will print true or false if the string starts/ends with the given string
           • stringname.split(" ") will separate strings with the string given
           • stringname.split(" ") will make a list of the words in a string separated by the string given
   • can be defined as other variables (eg: my = m + y)
   • you can define many at the same time (eg: a, b = 1, 3)

3. lists

   • listname = [] will create a new list
   • listname.append(1) will add 1 to the list

4. arithmetic operations

   • % used to get the remainder (eg amount left over after dividing od integers)
   • ** to make power relationships (eg 7 to the power of 2 will be: 7 ** 2)
   • conditions
     • x == 3 will return true if x equals 3
     • x != 3 will return false
     • operators
       • two == are used to compare bolean values
       • != is not equals operator
       • < and > are greater and smaller operators
       • and/or are used to make complicated boolean expressions (eg: if name== john and age == 32 print your name is...)
       • "in" will check if the object exists in an iterable object container such as list
       • if/elseif will do an action if the statement given is true (eg: if x == 3 print "good")
         • if x > 15:
         • (4 spaces) print x
       • "not" will invert boolean values (eg:print not true will print false )
       • "is" does not match the values of the variables but the instances instead
         • eg (a = [1,2,3] b = [1,2,3] a is b. will print true but if you done b = a a is b would return true )

5. loops

   • for
     • for w in <list, array etc>
     • repeats fixed number of times
   • while
     • while <condition>
     • will repeat as long as the condition is true
   • continue/break are used to either skip the data block and go to the top of the loop or to stop it

6. functions

   • def functionname(arguments)
   • they can be called to perform a piece of code specified before
   • can return a variable (eg : return a will return the value of a)
   • functionname(arguments) will call a function