Development of programs is the art of preparing and designing necessary structures to come up with computer instructions that can be used to accomplish a task in the computer. There are six procedural steps involved in program development namely:
1> Problem recognition
2> Problem definition
3> Program design
4> Program coding
5> Program testing and debugging
6> Implementation and maintenance
There should be some kind of uniformity and relevance in execution from one stage to another and in every stage, documentation is necessary. The diagram below elaborates this.
A> Talk to users in order to assess their situations
B> Understand problems that need solutions
C> Siege an opportunity to develop the new system
D> Study the new directive given by the management requiring a change in the status quo
E> Make a formal presentation of the system being designed
1> Syntax error
These are errors that originate from improper use of language syntax (grammar, spelling, spacing, punctuation and skipping syntax) syntax- is the set of rules that defines the combinations of symbols that are considered to be a correctly structured document or fragment in that language.
For example: in most programming languages, declaration lines end with a semi-colon, failure to insert a semi-colon can result into a syntax error
Consider this PHP code:
If words like “echo” is misspelled like “icho” or “?” is missing at the start line or end line or quotations are missing in the statement “My first PHP script!" can lead to syntax error
2> Logical errors
Example: consider the PHP code above
The user may mistakenly alter the statement i.e. instead of typing echo "My first PHP script!" he/she types echo "My second PHP script!"
The code will execute but the output will be wrong. Therefore, logical errors are done due to entry of logical parameters
- There are several methods of testing the program for errors. These include:
1> Desk checking (dry-run)
This involves going through the program while still on paper before entering it in the program editor. This helps the programmer to detect the most obvious syntax and logical errors
2> Using debugging utilities
This involves entering the program in the program editor and trying to run debugging utilities to correct syntax errors
3> Using test data
The programmer enters various data variations and extremes including data with errors to test whether the system will grind to halt
- This is the actual delivery and installation of the new program to be ready for use.
Proper training and post implementation support of users will always reduce the chances of having those entering invalid data that can crash the program.
Six Steps of PDLC
1. Give one advantage of compiling a program rather than interpreting it
2. Outline at least six stages of program development in their respective order
3. Highlight two disadvantages of monolithic programs
4. State two advantages of modular programming
5. In what stage of the development does program documentation justify your answer
6. Differentiate between a flowchart and pseudo code
7. What is a program bug?
8. Explain why it is important to test a program before implementing it.
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