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2.3 Validation (Methods of validating user input (Correct data type,…
2.3 Validation
Defensive Design
Anticipate problems before they happen
Assume all users are idiots
Design your program accordingly
Results in more robust program
Isn't full of bugs
Doesn't crash
input validation
Check ALL data entered into a system is valid
Input Sources
Form
Read from file
Generated by algorithm
Passed as a parameter
Methods of validating user input
Correct data type
within permitted range
Required filed entered
Correct format
Correct length