dictionary of programming concepts

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list of entries

  1. constant values
  2. output
  3. variables
  4. input
  5. basic math
  6. loops
  7. conditionals
  8. functions

constant values

a value is a piece of information-- it can be a number, a string of characters (text) or anything else that the computer can represent as a series of 1s and 0s. examples: "hello there" -7.5 11 the first value is a string of text, the second value is a negative non-integer (known as a float value) and the third value is an integer. integers and floats are "numeric" values. back to list


a type of command that moves information from the program to a device or file. examples: print "hello world" pset 5, 10 filename.write(p) the first example puts text on the screen, the second places a dot at coordinates 5, 10 on the screen, the third example adds the contents of *p* to a file. *p* is a variable. back to list


a variable is a value that is given a name-- you can change the value, so the pairing is called a "variable". examples: user = "roy" height = 11.5 count = 100 back to list


a type of command that moves information to the program, from a device or file. typically the information is stored in a variable. examples: height = raw_input() inputfile = open("file.txt").read() back to list

basic math

everything the computer does, consists of moving numbers around to numeric locations. the modern computer is a glorifed calculator with expensive outputs and inputs. examples: variablename = secondvariable + variablename / 2 height = abs(int(raw_input())) back to list


a loop is typically a section of code, the top and bottom of which are marked with a pair of statements, a pair of braces, or levels of indentation. the code between the top and bottom run repeatedly, until a condition (comparison of values) is true or a certain number of loops is reached. examples: while now print wend for p, 1, 10, 1 now = p ; print next for each in arrayitems: print each back to list


the concept of program loops predate the modern (20th century) computer, and loops can have a conditional that tell them when to stop repeating-- a conditional is code that "loops" either 1 time or 0 times, depending on a condition. the condition is typically a comparison of values. a condition of "true" is a value that is not equal to 0. examples: if this_variable_is_not_0: print "true" ifmore p, 11 now = "p is not 11 or less" ; print next while count = getcount p ifequal count, 200 break # stops loop next wend back to list


functions help you organise code that is likely to be useful more than once in a program-- it is also like creating your own command, though it will only exist in programs where that command is defined. to add a function from one program to another, you either need to "import" the command from a library, or copy the code into the new program. since basically all commands in a programming language are sections of code that are called by their name, you can refer to commands in a language as "functions" or "routines". in oop languages, a function is also known as an "object method". functions are "defined" (created) and then "called" (run from the program.) as with any other command, you call a function by using its name. you define it by writing code in it: examples: # a python function def greet(p): print "hello, " + p # a fig function function greet p now = "hello, plus p is not 11 or less" ; print next # calling a python function greet("rms") # calling a fig function (the = sign is optional) now = greet "milo" back to list

[lit]happy coding![lit]