Summary Programming Logic and Design Ch 3

Chapter 3
Describe the disadvantages of unstructured spaghetti code
 Spaghetti code - Logically twisted program statement, complicated mess
 Programs work, but are difficult to read and maintain, confusing and prone to error
 Unstructured programs - do not follow rules of structured programs
 Structured programs - do follow the rules of structured programs

Describe the three basic structures
 Structure - Basic unit of programming logic
 Any program can be constructed using one or more of these three structures
 Sequence structure
 Perform actions in order
 No branching or skipping any task
 Selection structure (decision structure)
 Ask a question, takes one of two actions (only true or false)
 Also, decision structure or selection structure
 Boolean expression- decision statement (if)
 Dual-alternative ifs or single-alternative ifs
 contains two alternatives (if-then-else endif)
 contains only one alternative (if-then endif) else not required (if it rains then take an
umbrella)
 null case - situation where nothing is done (if it does not rain, do nothing)
 end structure statement- endif


 Loop structure
 Repeat actions while a condition remains true
 Loop body- actions taken within loop
 also called repetition or iteration
 condition tested first in most common form of loop
 (while...do) or (while) loop


 Combining structures
 Structures can be combined in an infinite number of ways
 Any individual task or step in a structure can be replaced by a structure
 Stacking structures - attaching structures end-to-end
 End structure statement- indicates end of structure (endif) (endwhile)
 Nesting structure - placing one structure within another, indent the nested structure's
statements
 Block - a group of statements that execute as a single unit