Programming Basics

Programming Basics

1. Data Types

   • programming languages Have Five Main Data Types
     • Interger, int, Whole numbers only
     • Real(float), real, Numbers that have a decimal place
     • Boolean, bool, Can only take 2 values, usually TRUE or FALSE
     • Character, char, A single letter, number or symbol
     • String, STRING, Used to represent text, it is a collection of characters

2. Operators

   • the Basic Arithmetic Operators are straightforward
     • the arithmetic operators take two values and perform a maths function on them
     • Addition, subtraction, multiplication and divison operators do what you'd expect
     • The exponentiation operator is used to raise a number to a power
     • The DIV operator returns the whole number part of a division and the MOD operator gives a remainder
   • Assignment and Comparison Operators
     • The assignment operator, =, is used to assign values to constants or variables
     • A common mistake is to get the assignment operator = and the comparison operator == mixed up --- you'll know you've used them incorrectly because your code won't behave as intended

3. Constants and Variables

   • Data Values can be Constant or Vairables
     • Data values can be stored as constants or variables
     • The name of the constant or variable is linked to a memory location that stores the data value. The size of the momory location depends on the data type
     • A constant is assigned a data value at design time that can't be changed. If you attempt to change the value of a constant in a program then the interpreter or complier will return an error
     • Variables in the other hand can change value which them far more useful than constants
     • Constants and variables often need to be declared (at the stat of the program) before you can use them.

4. Strings

   • Strings are written inside Quotation marks
     • Strings are usually written inside double quotation marks ", but sometimes singles quotes are used '
     • Strings can be joined together ---- to form new strings ---- this is called concatenation. it's often done using the + opeator
   • Programs let you Manipulate Strings in a variety of ways
     • Before getting started on string manipulation you should know that the characters are usually numbered starting at 0
     • common string manipulation functions needed for the exam are: x.upper-changes all strings in x to upper case, x.lower-changes all characters in string x to lower case, x{i}-extracts the character in position i from string x and x.sunstring(a, b)-extrqcts a string starting at position a with length b from string x

5. Program flow