Problem Solving and Design

Verification is a check that the data entered into the system matches the data that was intended.

Validation asks "Is this input sensible?" Verification asks "Did the user actually mean to type this?"

Two common verification methods:

Double-entry verification

The user enters the same value twice; the program checks that the two entries match.

Example — When setting a new password, the user is asked to type it once and then again in a second box. If the two entries differ, the password is rejected.

Pseudocode:

INPUT password
INPUT confirm_password
WHILE password <> confirm_password DO
   OUTPUT "Passwords do not match"
   INPUT password
   INPUT confirm_password
ENDWHILE

Visual check

The system displays the entered data back to the user and asks them to confirm it is correct before continuing.

Example — At an online checkout, after the user types in their delivery address, the page shows the address back and asks "Is this correct?" with Yes/No buttons.

When to use which

• Double-entry verification is best for values the user cannot easily check by reading (passwords, where the characters are usually masked).
• Visual verification is best for values the user can easily eyeball (addresses, names, phone numbers).

The big-picture difference