Searching and sorting; validation and verification

Totalling means adding values into a running total: `Total ← Total + Value`.

Counting means adding 1 each time something happens: `Count ← Count + 1`.

Both variables must start at 0 before the loop.

DECLARE Marks : ARRAY[1:6] OF INTEGER
DECLARE Index : INTEGER
DECLARE Total : INTEGER
DECLARE PassCount : INTEGER
// Marks already holds 34, 48, 21, 40, 15, 45
Total ← 0
PassCount ← 0
FOR Index ← 1 TO 6
  Total ← Total + Marks[Index]
  IF Marks[Index] >= 25
    THEN
      PassCount ← PassCount + 1
  ENDIF
NEXT Index
OUTPUT "Total: ", Total
OUTPUT "Number of passes: ", PassCount

marks = [34, 48, 21, 40, 15, 45]
total = 0
pass_count = 0
for index in range(6):
    total = total + marks[index]
    if marks[index] >= 25:
        pass_count = pass_count + 1
print("Total:", total)
print("Number of passes:", pass_count)

To find the maximum (largest), keep a variable `Highest`. Compare each value with it. If the value is bigger, it becomes the new `Highest`.

The minimum (smallest) works the same way with `Lowest` and `<`.

Start `Highest` at the smallest possible value and `Lowest` at the largest possible value. Another safe way is to start both at the first item.

DECLARE Marks : ARRAY[1:6] OF INTEGER
DECLARE Index : INTEGER
DECLARE Highest : INTEGER
DECLARE Lowest : INTEGER
// Marks already holds 34, 48, 21, 40, 15, 45 (each out of 50)
Highest ← 0
Lowest ← 50

FOR Index ← 1 TO 6
  IF Marks[Index] > Highest
    THEN
      Highest ← Marks[Index]
  ENDIF
  IF Marks[Index] < Lowest
    THEN
      Lowest ← Marks[Index]
  ENDIF
NEXT Index

OUTPUT "Highest: ", Highest
OUTPUT "Lowest: ", Lowest

marks = [34, 48, 21, 40, 15, 45]
highest = 0
lowest = 50
for index in range(6):
    if marks[index] > highest:
        highest = marks[index]
    if marks[index] < lowest:
        lowest = marks[index]
print("Highest:", highest)
print("Lowest:", lowest)

The lesson page has the rest of the explanation, step by step:

• Finding the average
• Linear search
• Bubble sort
• How many comparisons? (extra)
• Validation and verification are different
• Range, length, type and presence checks
• Format and check digit checks
• Writing a validation loop
• Verification: visual check and double entry
• The four types of test data
• Worked example: a test plan

Open the lesson page