4.1.5. Data Constraints

In addition to representing data with different data storage methods, computers can also let you add additional constraints on what can be saved. So, for example, you might limit the length of a tweet to 280 characters, even though the computer can store longer strings.

There are many places these constraints might be used such as:

• for an age (integer), only allow ages between 0 and 120

• for a country name (string), have a pre-set list of valid country names

• for a legal name (string), disallow emojis