Flow Control Analysis & Design Tool: Flowcharts Flowchart - a graphical way of writing algorithms...
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Transcript of Flow Control Analysis & Design Tool: Flowcharts Flowchart - a graphical way of writing algorithms...
Flow Control Analysis & Design Tool: Flowcharts
• Flowchart - a graphical way of writing algorithms
– Rectangle is used for calculations
– Parallelogram is used for input and output
– Circle is used as connector
– Diamond is used as decision
– Symbols are connected by arrows to represent the order of the operations
Flowcharts Symbols: Calculations
Calculations (e.g. arithmetic expressions) are shown in rectangles
Examples: Total = Cost + Tax
Num = Num + 1
Total = Cost + Tax
Num = Num + 1 (add one to the current value of Num and make that the new value of Num)
Flowcharts Symbols: Input/Output
Data input and output are shown in parallelograms
Input means a read operation of data from a peripheral device to memory (e.g. a user typing in data at a keyboard)
READ Num
WRITE Num Output means a write operation of
data to a peripheral device from memory (e.g. data displayed to the monitor)
Flowcharts Symbols: Decisions
Decisions are shown within diamonds and specify a condition to be tested
Based on the condition being TRUE or FALSE, the next operation will be determined
Gross > 50000
Rate = 0.31
Rate = 0.28True
False
A decision is composed of : A condition An operation to be done if
condition is TRUE Possibly an operation to be done if
condition is FALSE
Flowcharts Symbols: Start and End
Every algorithm starts somewhere and terminates somewhere
Every flowchart must have one start symbol and one end symbol
Start and end symbols are ovalssquare = num x num
input num
print square
start
stop
A start symbol denotes the start of the algorithm
An end symbol indicates the algorithm has terminated
Sequential AlgorithmFlowchart
• Pseudocode Algorithm:
– PROMPT for Age of Child1
– READ Age of Child1
– PROMPT for Age of Child2
– READ Age of Child2
– CALCULATE Allowance for Child1 = Age of Child1 x Rate
– CALCULATE Allowance for Child2 = Age of Child2 x Rate
– DISPLAY Allowance for Child1
– DISPLAY Allowance for Child2
Allow1 = Age1 x Rate
input Age1
start
Print Allow1
stop
prompt Age1
Allow2 = Age2 x Rate
Print Allow2
input Age2
prompt Age2
Selection AlgorithmFlowchart
• Previous Pseudocode Algorithm:
– PROMPT for Age
– READ Age
– IF Age less than 10
• THEN CALCULATE Allowance = Age x YoungRate
• ELSE CALCULATE Allowance = Age x OlderRate
– DISPLAY Allowance
Allow = Age x YoungRate
start
Print Allow
stop
prompt Age
Allow = Age x OlderRate
Age < 10 FALSETRUE
input Age
Looping AlgorithmFlowchart
• Previous Pseudocode Algorithm:
– Set KidsPaid to 0
– Set Total to 0
– WHILE KidsPaid < 3 DO
• PROMPT for Age
• READ Age
• CALCULATE Allowance = Age x Rate
• ADD Allowance to Total
• INCREMENT KidsPaid
– DISPLAY Total
start
Display Total
stop
Read Age
Calc Allowance
KidsPaid < 3FALSETRUE
KidsPaid = 0
Total = 0
Add Allowance to Total
Increment KidsPaid
Prompt Age