Programming

Programming

1. Data Types

   • Integer
     • A negative or positive whole number
   • Real/Float
     • A negative, positive, rational, irrational or whole number. Includes fractions and decimals
   • Boolean
     • This a truth value (which can be either true or false). Boolean expressions use the operators AND, OR, XOR and NOT to compare values and return a true or false result.
   • Character
     • A character is any letter, number, space, punctuation mark, or symbol that can be typed on a computer.
   • String
     • This holds any number, symbol or text. Although mainly used for text/symbols alone
   • Date/time
     • This stores data in the format that is easily identifiable as Date or time. e.g. 12.03.14 or 12:30
   • Records
     • One line of a text file
   • Arrays
     • A set of related data items stored under a single identifier, this cab work on one or two dimensions

2. Programming concepts

   • Variable
     • A data item whose value CAN change while the program is being run
     • Local
       • These can only be called in their subroutine and exist only while the subroutine is executing. This increases the modularity and decreases the volume of memory used
     • Global
       • These are assigned memory at run-time, the memory is only released when the program closes, these variables can be called from all blocks this means they may be called and edited accidentally
   • Constant
     • A data item whose value CANNOT be changed while the program is being run
     • Advantages of named constants
       • You know what the constant is storing, this makes it easier for error handling and using the constant throughout the program
   • Assignment
     • The process of giving a value to a variable or constant. e.g. Balls = 2
   • Iteration
     • A process wherein a set of instructions or structures are repeated in a sequence a specified number of times or until a condition is met
       • Definite
         • The process is repeated a set umber of times
       • Indefinite
         • The process is repeated until the certain condition is met.
   • Selection
     • The principle of using comparison to chose what action should be taken based on a certain criteria
   • Subroutine
     • A set of instructions designed to perform a frequently used operation within a program
     • Advantages
       • Makes code easier to understand, they can be used anywhere in the program so avoids the need to repeat large chunks of code, they also make the program easier to debug
     • Parameters
       • These are a special kind of variable used in a subroutine to refer to one of the pieces of data as an input to the subroutine
   • Nested selection
     • A selection statement (eg. if/case) inside another selection statement
   • Meaningful identifier names
     • These allow a new user to understand the program more easily, they also describe what the variable is going to be used for
   • Nested iteration structure
     • A loop inside of another loop, they can be used to create columns and rows

3. Arithmetic Operations

   • Addition
     • +
   • Subtraction
     • -
   • Multiplication
     • *
   • Division
     • DIV
     • /
   • Remainder
     • MOD
   • Rounding
     • Rounds the number up
   • Truncation
     • Cuts off the number, adding zeros after, where it is asked

4. Relational Operations

   • Equal to
     • =
   • Not equal to
     • <>
   • Less than
     • <
   • Less than or equal to
     • <=
   • Greater than
     • >
   • Greater than or equal to
     • >=

5. String-Handling Operations

   • Length
     • Returns the number of characters in the specified code
   • Position
     • Returns the position of the specified character in the code, inclusive of special characters
   • Concatenation
     • Joins two strings together
   • Substring
     • Looks for a string within another string, it returns TRUE if it's found.

6. Random Number Generation

   • Given a minimum and maximum range it will produce a new random number when the function is called (Randomize)

7. Exception Handling

   • When an error occurs the try-catch block allows for the program to handle the exception without the program crashing or losing any data