Validation & Verification
边玩边学
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课程笔记
Validation & Verification Overview
- Validation is an automated process checking if input is sensible and meets program requirements.
- Verification checks that data entered matches the original intended data (accuracy).
- Validation ensures data is possible/reasonable; verification ensures it is correct.
Types of Validation Checks
- Range check: ensures a number falls within a specified range (e.g., 0–100).
- Length check: ensures a string has a required number of characters (e.g., PIN = 4 digits).
- Type check: ensures data is of the correct data type (e.g., integer, string).
- Presence check: ensures a field is not left blank.
- Format check: ensures data matches a pattern (e.g., XX9999, email with @ and .).
- Check digit: a final digit calculated by algorithm to detect errors in codes (e.g., ISBN).
Verification Methods
- Double entry: data entered twice; system compares both entries; mismatch triggers error.
- Visual check: user reviews data on screen and confirms correctness (e.g., popup).
- Example: password confirmation uses double entry; name entry uses visual check.
Suitable Test Data Categories
- Normal data: valid input that should be accepted (e.g., age 16 for range 12–18).
- Abnormal data: invalid data type or value that should be rejected (e.g., 'H' for age).
- Extreme data: boundary values that are still acceptable (e.g., 12 and 18).
- Boundary data: values just inside and just outside the acceptable range (e.g., 11, 19).
Trace Tables
- A trace table records the state of variables and outputs at each step of an algorithm.
- Used to detect logic errors in flowcharts, pseudocode, or program code.
- Each row corresponds to one step/iteration; columns for inputs, outputs, and variables.
- Helps discover the purpose of an algorithm by showing intermediate results.
Flowchart showing how data passes through validation and verification before acceptance.
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练习题
免费预览——58 题中的 8 题。注册即可查看全部。
1.What is the purpose of validation?
Easy- ATo check that data entered is sensible and meets program requirements
- BTo check that data entered is exactly what was intended
- CTo check that data is stored correctly in the database
- DTo check that data is transmitted without errors
2.A program asks the user to enter a password. Which two validation checks would be most appropriate for a password field?
Medium- ALength check and presence check
- BRange check and type check
- CFormat check and check digit
- DPresence check and range check
3.A program uses the following pseudocode to validate input: REPEAT INPUT Number IF Number < 0 OR Number > 100 THEN OUTPUT "Invalid" ENDIF UNTIL Number ≥ 0 AND Number ≤ 100 Which type of validation is being performed?
Easy- ARange check
- BLength check
- CType check
- DPresence check
4.Which of the following is an example of verification?
Easy- ADouble entry checking
- BRange check
- CFormat check
- DCheck digit
5.A website registration form asks users to enter their email address twice. This is an example of:
Easy- AVerification using double entry
- BValidation using format check
- CValidation using presence check
- DVerification using visual check
6.An ISBN number ends with a check digit. What is the purpose of the check digit?
Easy- ATo help detect errors when the number is entered or transmitted
- BTo ensure the number is in the correct format
- CTo verify that the number belongs to a valid book
- DTo encrypt the number for security
7.Which validation check would reject the input "ABC" for an age field?
Easy- AType check
- BRange check
- CLength check
- DPresence check
8.A program checks that a username is not left blank. Which validation check is this?
Easy- APresence check
- BLength check
- CType check
- DFormat check