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Writing readable code and from algorithms to programs
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Code is read far more often than it is written. Clear code is easier to fix, improve and share.
Making code readable
Comments (starting with #) explain what code does and why.
Meaningful identifiers such as total_price instead of tp or x.
Indentation shows the structure of loops, ifs and subprograms (and is required in Python).
White space and blank lines separate sections. A clear layout keeps related code together.
Meaningful identifiers such as total_price instead of tp or x.
Indentation shows the structure of loops, ifs and subprograms (and is required in Python).
White space and blank lines separate sections. A clear layout keeps related code together.
Structural components
Look for these in any program: constants and variables, initialisation (total = 0), assignment, sequence, selection (if), repetition (while, for), iteration over a data structure, data structures (lists), subprograms with parameters, and input/output.
From algorithm to program
Each flowchart or pseudocode part becomes a Python construct:
Process box → assignment. Decision diamond → if or a loop condition. Input/output box → input() or print(). Arrow back up to an earlier step → a loop.
This program adds up the positive numbers among 5 inputs:
total = 0
for count in range(5):
num = int(input("Number: "))
if num > 0:
total = total + num
print(total)
Process box → assignment. Decision diamond → if or a loop condition. Input/output box → input() or print(). Arrow back up to an earlier step → a loop.
This program adds up the positive numbers among 5 inputs:
total = 0
for count in range(5):
num = int(input("Number: "))
if num > 0:
total = total + num
print(total)
The program in step 3 is given the inputs 4, -2, 7, 0, 3. What is output?
- Only positive numbers are added: 4, 7 and 3.
- 4 + 7 + 3
Answer: 14
Comments, meaningful identifiers, indentation and white space make code easy to maintain. Decision symbols become if statements or loop conditions; process boxes become assignments.
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