Defining New Types

Notes for the required material 

• These notes can be purchased in the Student Union Copy Center at cost
• Defining new types in Pascal (Leestma & Nyhoff : Chapter 8 (Enumerated types and Subranges): [PowerPoint] [Acrobat]

Optional teaching material

Background / Sources of additional information

• Pascal Programming and Problem Solving by Leestma S. and Nyhoff L. 4th Edition (MacMillan Publishing Company).
• Pascal an Introduction to the Art and Science of Programming by Savitch W.J. (The Benjamin / Cummings Publishing Co., Inc.). 
• The Pascal link under the GNU website (ssince the U of C Computer Science department uses the GNU Pascal compiler gpc).

Teaching Tips

Although many instructors teach the material in this section prior to talking about arrays I don't do this because in my opinion the introduction to composite types such as arrays is complicated enough without adding the additional complexity of learning about how to define a new types.   While there are some benefits to type-defining arrays (such as type checking) and in some cases it is mandatory in Pascal (when passing arrays as parameters to functions and procedures) it can also make the code harder to read.  When you see an instance of the new type you have to keep going back to the type definition in order to determine what that type consists of (e.g., to determine the boundaries for the type-defined array).