In pseudocode, functions and procedures are used to divide a program into smaller, manageable parts. They help improve clarity, reduce repetition, and make algorithms easier to understand and maintain. A procedure is a block of code that performs a specific task and may accept input values but does not return a result, while a function performs a task and returns a single value to the part of the program that called it. Both functions and procedures are essential in Cambridge A Level Computer Science, as they demonstrate structured programming and are commonly used in exam-style problem solving
Question #1: Write pseudocode to validate a given password. For a password to be valid it must contain:
- at least two lower case letters
- at least two uppercase characters
- at least three digits
- minimum 8 characters long
Write a function
ValidatePassword that will check if the given password follows the above rules. This function takes a parameter
Pass as a parameter and returns
TRUE if it is valid and
FALSE otherwise.
FUNCTION ValidatePassword(Pass: STRING) RETURNS BOOLEAN
DECLARE Result: BOOLEAN
DECLARE Lcase: INTEGER
DECLARE Ucase: INTEGER
DECLARE len: INTEGRER
DECLARE Letter: CHARACTER
Lcase ← 0
Ucase ← 0
Digits ← 0
Len ← LENGTH(Pass)
FOR x ← 1 TO Len
Letter ← MID(Pass,x,1)
IF Letter >= 'A' Letter <= Z THEN
Ucase ← Ucase + 1
ELSE IF Letter >= 'a' AND Letter <= 'z' THEN
Lcase ← Lcase + 1
ELSE IF Letter >= '0' AND Letter <= '9' THEN
Digits ← Digits + 1
ENDIF
NEXT x
IF len >= 8 AND Lcase >= 2 AND Ucase >= 2 AND Digits >= 2 THEN
Result ← True
ELSE
Result ← False
ENDIF
RETURN Result
ENDFUNCTION
Description
- The LENGTH() function accepts a string as its argument and returns the total number of characters in the string.
- The MID(str, x, y) function extracts a substring of length y from the string str, starting at position x.
- Pass is a variable that stores the password value received by the function.
- Letter is a variable that stores a single character extracted from the string using the MID() function.
STACK PROGRAM
Write pseudocode for implementing a stack using array. Use the following procedures for stack operations:
Push() – Accepts an integer value to be pushed into the stack.
Pop() – to remove an item from the stack
and Display() – to display the content of the stack.
Display a menu to choose the stack operations like, Push, Pop, Display and Exit.
DECLARE MyStack: ARRAY[1,5] OF INTEGER
DECLARE Choice: INTEGER
DECLARE Max: INTEGER
DECLARE Top: INTEGER
DECLARE Bottom: INTEGER
PROCEDURE PUSH(val : INTEGER)
IF Top = StackFull THEN
OUTPUT "Sorry, Stack Full"
ELSE
Top ← Top + 1
MyStack[Top] ← Val
ENDIF
ENDPROCEDURE
PROCEDURE DISPLAY()
IF Top = 0 THEN
OUTPUT "Stack is Empty"
ELSE
ind ← Top
WHILE ind > 0
OUTPUT MyStack[ind]
ind ← ind - 1
ENDIF
ENDPROCEDURE
PROCEDURE POP()
IF Top < 1 THEN
OUTPUT "Stack is Empty!"
ELSE
OUTPUT MyStack[Top],"has been removed from stack"
Top ← Top - 1
IF Top = 0 THEN
Bottom ← 0
ENDIF
ENDIF
ENDPROCEDURE
StackFull ← 5
Top ← 0
Bottom ← 0
REPEAT
OUTPUT "1. PUSH"
OUTPUT "2. POP"
OUTPUT "3. DISPLAY"
OUTPUT "4. EXIT"
OUTPUT "Enter your choice"
INPUT choice
CASE Choice OF
1: OUTPUT "Enter a number to push"
INPUT num
PUSH(num)
2: POP()
3: DISPLAY()
ENDCASE
UNTIL Choice = 4
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