Unit 2A Programming 12/11/19

Unit 2A Programming 12/11/19

1. Data

   • There are different types of data such as characters,strings,floats (decimals)
     • A sting is 1 or more characters "37" is a sting because it has speech marks
       • When you adding two string: stringA= "2" stringB="5" stringA+stringB=25 . You do not add them because they are not integers you put the two stings together
       • A Substring is a string that you get from the original string
         • e.g scien is a substring of computerscience
   • Raw facts and figures before they have been processed
   • Information is processed data

2. Constant

   • typically shown in uppercase
   • Data values that stay the same every time a program is executed are known as constants. Constants are not expected to change.
   • It is a temporary memory location

3. Variable

   • A variable is a location in a memory in which you can temporarily store texts or numbers
   • Rules for python: A variable name must start with a letter or the underscore character
   • Declaring a variable:you give it a name and a type(string/int/char/float). In python you don't need to write the type, python will assume the type
     • Initializing a variable is when you assign a specific value to the variable. This uses the assigning construct

4. Arithmetic operators

   • The operation DIV is used for integer division
     • For example 17 DIV 3=5
   • MOD -Modulus- is used to find the remainder when dividing one integer by another
   • Exponent ^ e.g 5^2 =25
   • Remember BODMAS when calculating

5. INPUT Statement

   • In some languages, such as python you can combine a user prompt with an input statement e.g
   • In python all input is assumed as a string. Therefore if you are inputting an integer or a real number, you have to convert it before it can be used in the calculation

6. Concatenating Strings

   • Strings can be joined together to form a new string of data. This is called concatenation. We use the + symbol to concatenate strings. For example:

7. Using comments

   • we use comments to: describe the aim of the program, to state the author of the program, to explain what the code does.
   • Comments start with a # sign
   • They are ignored when your program is translated to machine code and executed

8. len is the length, a is the length of the string which is 32(you count the spaces), when you are counting the position start counting from 0 and include the spaces. e.g "milk" is position 8. The fourth line- you take the 11th position to the 17th position.Including the 11th position but excluding the 17th position(k a ya).

   • ARRAYS

9. Programming constructs

   • Assignment
   • Sequence -when instructions are executed in the order that they are written in consecutively.
   • Selection-An IF statement is a selection statement. A program branch depending on a decision
   • Iteration-sometimes called a loop, is a repeating section of a code.FOR … END FOR, WHILE … ENDWHILE , REPEAT … UNTIL
     • WHILE loop does something while the condition is true- condition control loop
       • repeat.. until the condition is checked at the end. while..endwhile the condition is checked at the beginning
     • FOR...ENDFOR- use when you know how many times the code is repeated- count controlled loop
     • Counter controlled iterations are used when you want to iterate a known number of times.• Counter controlled iterations use a variable which can be used within the code to know how many times the code has been run.
     • • Code must be indented within an iteration.
   • nested selection statement- an if statement within an if statement
   • • Incrementing a variable increases its value by one. • Decrementing a variable decreases its value by one.

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