2.1.4 Thinking Logically Flashcards
1
Q
What is Logic
A
- Use of logical operators to reason the outcome of a given arguement
- Thinking logically is the process of combining logical operators and data sets to produce logical expressions that represent complex arguments and identify possible outcomes
2
Q
What are examples of some logical operators
A
- > - Greater Than
- < - Less than
- <= - Less than or equal to
- >= - Greater than or equal to
- != - Not equal to
- == - Equals (same as)
3
Q
What do the logical operators: AND, NOT, OR and XOR mean
A
- AND - Both statements must be true for the argument to be true
- OR - Only 1 statement has to be true or both for argument to be true
- XOR - (exclusive OR) - Argument is false if both statements are true or both are false
- NOT - The opposite of
4
Q
When do decisions have to be taken
A
- Happens during selection, which 1 of a number of alternative paths are chosen based on teh condition of a logical operation.
- Also during iteration whether or not to repeat a set of instructions
- Draw a flowchart to identify where decisions need to be taken (see decision diamond) - require logical operators to be used.
5
Q
How do you determine the logical conditions that affect the outcome of a decision.
A
- Can be difficult to determine. The basic methodology is to take the problem or conditions and write them out and rewrite them using logical operators and remove extra text.
- This process should leave with a logical argument that can be turned into selection or iteration.
6
Q
How do you determine how decisions affect flow through program
A
- Determining how decisions affect flow through a program is simple with a flowchart but is hard to choose an implementation method
- Selection statement represents a single decision but can use else if to code alternative values. Can be nested to give multiple decisions
- Iteration involves repetition of code. Should look for arrows that loop to earlier instructions. Therefore implemented as an iteration.
