Programming Basics

• A data type determines what data can be stored in a variable and how it should behave
• An integer stores positive and negative whole numbers
• A float or real can store positive and negative fractional numbers as well as integers
• A string stores any sequence of alphanumeric characters
• A character or char stores any single alphanumeric character
• A date/time data type stores dates and/or times in accordance with the real-world calendar
• A Boolean data type holds a Boolean value of true or false, typically represented as a 1 or 0
• A record can store various data of differing data types using named fields
• An array is a sequence of elements of the same data type with a fixed size
• A list is a sequence of elements of the same data type with an undefined size
• A pointer/reference stores a variable that points to an address in memory
• User-defined data types are data types constructed by the user. They can be more complex and have many uses such as creating records.
• Assignment occurs when a variable is given a new value
• All coding statements fall into one of three programming constructs: sequence, selection and iteration
• Sequence means the code is executed one line at a time in order
• Selection occurs when different code is executed according to conditions, allowing the program to branch (make choices)
• Iteration is when a group of statements is repeated multiple times (looping)
• In a count-controlled loop, instructions are repeated for a fixed number of times declared at the start of the loop. This is called definite iteration
• In a condition-controlled loop, instructions are repeated until a condition is met, defined either at the start or the end of the loop. This is called indefinite iteration
• An exit condition at the start of the loop means it may execute 0 or more times
• An exit condition at the end of the loop means it may execute 1 or more times
• Nested statements allow selection and iteration to occur within other selection and iteration statements
• A subroutine is a section of code that can have parameters passed into it, and be called and reused multiple times throughout a program
• A procedure is a subroutine that executes code but does not return a value
• A function is a subroutine that executes code and then returns a value
• An identifier is a name given to an entity in a programming language, such as to a variable or data type
• Sensible identifier names should be used to make your code easy to read and understand
• A variable is a named location in memory
• The contents of a variable can change while the program is running
• The contents of a constant cannot change while the programming is running and can only be altered in the code
• Several mathematical operations can be performed on integers and floats
• To always round up, use Math.Ceiling
• To always round down, use Math.Floor
• Mod or modulo returns the remainder in a division operation. In C# this is done using the operator %
• Integer division returns an integer from any division operation, discarding any remainders
• = is used for assignment. == is used for comparisons.
• ^ is the exponentiation symbol, used to raise numbers to a power. In C#, this can be done using Math.Pow
• NOT is a logical operator that reverses a Boolean value
• AND is a logical operator that only returns true if both inputs are true
• OR is a logical operator that returns true if at least one input is true