Section 1
Preview this deck
%s
Front
| 5 | 0 | ||
| 4 | 0 | ||
| 3 | 0 | ||
| 2 | 0 | ||
| 1 | 0 |
Active users
0
All-time users
0
Favorites
0
Last updated
6 years ago
Date created
Mar 1, 2020
Cards (51)
Section 1
(50 cards)
%s
String A string is intended for general consumption. use %s (string) for anything that you want to show to an end user
%f
float Floating point decimal format
"
Every time you put " (double-quotes) around a piece of text you have been making a string. A string is how you make something that your program might give to a human. You print strings, save strings to files, send strings to web servers, and many other things. ' (single-quotes) also work for this purpose.
\'
Single-quote (')
%d, %i
Signed integer decimal
\v
ASCII vertical tab (VT)
ASCII linefeed (LF) - new line
\"
Double-quote (")
\a
ASCII bell (BEL)
\xhh
Character with hex value hh
True False
Python recognizes True and False as keywords representing the concept of true and false. If you put quotes around them then they are turned into strings and won't work.
%d
digit
''',"""
Free-form strings
open()
opens the specified file, it takes a parameter and returns a value you can set to your own variable.
How do I get a number from someone so I can do math?
That's a little advanced, but try x = int(raw_input()) which gets the number as a string from raw_input() then converts it to an integer using int()
%e
Floating point exponential format
%r
Raw string Representation: A representation is something that (might?) allow for some sort of round-trip, later (re)construction of the object. use %r if you are planning to (re-)consume your own printed output. You should use %s and only use %r for getting debugging information about something. The %r will give you the "raw programmer's" version of variable, also known as the "representation." prints the way you wrote it (or close to it).
from sys import argv
Called an "import." This is how you add features to your script from the Python feature set. Rather than give you all the features at once, Python asks you to say what you plan to use. This keeps your programs small, but it also acts as documentation for other programmers who read your code later. May access features other than "argv"
\N{name}
Character named name in the Unicode database (Unicode only)
\ooo
Character with octal value ooo
\Uxxxxxxxx
Character with 32-bit hex value xxxxxxxx (Unicode only)
"""
Use to make a string that needs multiple lines for the string text.
PEMDAS
Order of Operations: Mode of Operations: Parentheses Exponents Multiplication Division Addition Subtraction
round()
rounds the value contained in the ()
\
Escape What It Does: This \ (backslash) character encodes difficult-to-type characters into a string. There are various "escape sequences" available for different characters you might want to use. We'll try a few of these sequences so you can see what I mean. An important escape sequence is to escape a single-quote ' or double-quote ". Imagine you have a string that uses double-quotes and you want to put a double-quote inside the string. If you write "I "understand" joe." then Python will get confused because it will think the " around "understand" actually ends the string. You need a way to tell Python that the " inside the string isn't a real double-quote. To solve this problem you escape double-quotes and single-quotes so Python knows to include in the string. Here's an example: "I am 6'2\" tall." # escape double-quote inside string 'I am 6\'2" tall.' # escape single-quote inside string The second way is by using triple-quotes, which is just """ and works like a string, but you also can put as many lines of text as you want until you type """ again. We'll also play with these.
.read()
reads the specified file use by entering at the end of the variable used to specify the file you have 'opened'.
Write comments on code ...
No, you write comments only to explain difficult to understand code or why you did something. Why is usually much more important, and then you try to write the code so that it explains how something is being done on its own. However, sometimes you have to write such nasty code to solve a problem that it does need a comment on every line. In this case it's strictly for you to practice translating code to English.
=
(single-equal) assigns the value on the right to a variable on the left.
variables
can only start with a character (not a number)
\f
ASCII formfeed (FF)
import
This is how you add features to your script from the Python feature set. Rather than give you all the features at once, Python asks you to say what you plan to use. This keeps your programs small, but it also acts as documentation for other programmers who read your code later.
\b
ASCII backspace (BS)
int()
converts to integer
==
(double-equal) tests if two things have the same value.
"""
%x
Signed hexidecimal
\\
Backslash (\)
%
Modulus is NOT used as a "percentage" sign in the programming language
\t
Horizontal Tab (TAB) - Tab In
Floating Point Number
any number with a decimal point showing one or more digits behind the decimal point. e. "4.0" or "0.087"
%c
Single character
raw_input()
Use for asking a user questions. Creates a dialogue that asks for a user to input data. Use to create "forms". input() has security problems, so avoid using it For raw_input you can also put in a prompt to show to a person so he knows what to type. Put a string that you want for the prompt inside the () so that it looks like this: y = raw_input("Name? ")
\r
Carriage Return (CR)
argv
the "argument variable," a very standard name in programming, that you will find used in many other languages. This variable holds the arguments you pass to your Python script when you run it. You know how you type python ex13.py to run the ex13.py file? Well the ex13.py part of the command is called an "argument." What we'll do now is write a script that also accepts arguments. What's the difference between argv and raw_input()? The difference has to do with where the user is required to give input. If they give your script inputs on the command line, then you use argv. If you want them to input using the keyboard while the script is running, then use raw_input(). Line 3: script, first, second, third = argv Line 3 "unpacks" argv so that, rather than holding all the arguments, it gets assigned to four variables you can work with: script, first, second, and third. This may look strange, but "unpack" is probably the best word to describe what it does. It just says, "Take whatever is in argv, unpack it, and assign it to all of these variables on the left in order." (ex13.py)
modules
libraries or features
#
Octothorpe use for comments on the code, use to disable code placing a # at the beginning of a line or in the middle of a line tells python to ignore whatever is written on the line after the #
strings
A string is usually a bit of text you want to display to someone, or "export" out of the program you are writing. Python knows you want something to be a string when you put either " (double-quotes) or ' (single-quotes) around the text. You saw this many times with your use of print when you put the text you want to go inside the string inside " or ' after the print to print the string. Strings may contain the format characters you have discovered so far. You simply put the formatted variables in the string, and then a % (percent) character, followed by the variable. The only catch is that if you want multiple formats in your string to print multiple variables, you need to put them inside ( ) (parenthesis) separated by , (commas). It's as if you were telling me to buy you a list of items from the store and you said, "I want milk, eggs, bread, and soup." Only as a programmer we say, "(milk, eggs, bread, soup)."
,
We put a , (comma) at the end of each print line. This is so print doesn't end the line with a newline character and go to the next line
%o
Signed octal value
\uxxxx
Character with 16-bit hex value xxxx (Unicode only)
Section 2
(1 card)