Software Design and Development - Implementation

Assigning a value to a variable e.g. In reference language SET score TO 20 In Livecode put 20 into score

Using arithmetic (+, -, /, *, ^) e.g. In reference language SET total TO total + score In Livecode put total + score itno total

Joining two or more strings or substrings For example in Livecode: put firstname & “ “ & surname into fullname Would join first name and surname and include a space between both In Reference language: SET fullname TO firstname + “ “ + surname

< Less than > Greater than ≤ Less than or equal to ≥ Greater than or equal to = Equals ≠ Does not equal

An If statement IS NOT A LOOP. IF statements allow the program to make decisions. Conditions, such as score <10 are used within IF statements. IF score < 10 OR score >50 SEND ‘Try Again’ TO DISPLAY END IF This IF statements checks to see if a score is less than 10 or higher than 50

Nested IFs are IF statements inside IF statements. The nested parts only run if needed. IF score < 100 THEN SEND “Low Score” to DISPLAY ELSE IF score < 150 THEN SEND “Mid level score” TO DISPLAY ELSE SEND “High score” TO DISPLAY END IF END IF

Logical operators can be used in IF statements and conditional loops. AND – Both conditions must be true OR – One condition must be true NOT – The opposite outcome to what would logically apply (negation)

A simple condition has only one condition e.g. IF firstname = “Betty” The condition is = “Betty”

A complex condition has two or more conditions e.g. IF firstname = “Betty” OR firstname = “Trevor” The two conditions are = “Betty” , = “Trevor” AND /OR are used as part of complex conditions

Repetition and iteration are technical terms for loops. Repetition repeats a task set number of times. Iteration is the same but usually involves checking over the contents of an array until you achieve what you want to achieve e.g. find a number or get to the end of the array list .

A fixed loop will repeat all code held within the loop a set number of times only. E.g. For loop = 0 to 9 <code> Next loop The above loop would repeat 10 times</code>

A conditional loop repeats until a condition is met e.g. WHILE score < 10 <code> END WHILE This loop will repeat the code inside as long as the score variable holds a value that is less than 10</code>

ROUND is a pre-defined function, meaning the code to make it work already exists. If you use the ROUND function, the computer will round a value to a certain number of decimal places: SET size TO ROUND (measurement, 1) This takes the value of the measurement variable and rounds it to one decimal place. It then returns this new value to the size variable

RANDOM is a pre-defined function, meaning the code to make it work already exists. If you use the RANDOM function, the computer will generate a random number: SET bonusBall TO RANDOM(1, 59) This would generate a random number between 1 and 59 and returns this number to the bonusBall variable.

LENGTHis a pre-defined function, meaning the code to make it work already exists. If you use the LENGTH function, the computer will calculate the number of characters held in a string variable: SET numberOfCharacters TO LENGTH (firstname) This would take the value in the first name variable, calculate its length and returnsit to the numberOfCharacters variable. E.g. Jane would return 4

This algorithm checks that input is valid: Line 1 SEND “Enter a score between 1 and 99” TO DISPLAY Line 2 RECEIVE score FROM (INTEGER) KEYBOARD Line 3 WHILE score ˂1 OR score ˃99 DO Line 4 SEND “Error, enter valid number” TO DISPLAY Line 5 RECEIVE score FROM (INTEGER) KEYBOARD Line 6 END WHILE

This algorithm keeps a running total: Line 1 DECLARE total INITIALLY 0 Line 2 FOR loop FROM 0 TO 4 DO Line 3 RECEIVE number FROM (INTEGER) KEYBOARD Line 4 SET total TO total + number Line 5 END FOR It asks for and keeps a running total of 5 values.

To traverse an array means to use a loop to go through the array one item at a time. DECLARE allGrades INITIALLY [A, B, B, D, F] FOR EACH grade FROM allGrades DO IF grade = 'A' THEN SET a_total TO a_total +1 END IF END FOR EACH In the above example, each item in the all Grades array is checked one after another, with a running total also calculated.