Wednesday 13 June 2012

PROGRAM DEVELOPMENT PHASES



In program development, there are five main phases. These phases are a series of steps that programmers undertake to build computer programs. The program development phases guide computer programmers through the development of a program.

The five main phases of program development are as follows:


PROBLEM ANALYSIS PHASE
During the problem analysis phase, the programmer will interview the client to find out what the client’s needs are.

For example, the client might be a school that wishes to set up a school registration program. So the school administrator might tell the programmer that they need to record students’ data such as name, date of birth, gender, class, parents’ names, address and contact numbers.

PROGRAM DESIGN PHASE
Based on that, the programmer will design a flow chart that represents the needs of the client, which in this case is the school registration program.

CODING PHASE
Once the flow chart is confirmed, the programmer will perform coding.

TESTING AND DEBUGGING PHASE
The school registration program will be tested by the users at the client’s site. In this case, it will be the school office administrators. If there are any errors, the programmer will do a debugging of the program.


There are three types of errors uncovered during this phase: syntax errors, logic errors and run-time errors. 

Syntax Error
 When the code violates the syntax of the programming language, a syntax
error occurs.
A syntax error is caused by a wrong spelling in command and declaration. Other syntax errors include case sensitive, punctuation and wrong word command.
They either show up as you type the program code, or if you have turned off the automatic syntax error check, the syntax errors show up when you try to run or compile the program.
When syntax error is located, a message is displayed on the screen.
The programmer must review and correct all syntax errors. 

 Logic Error
 If the expected output and actual output do not match for any set of data, the program has a logic error.
A logic error is an error in the design that causes inaccurate outputs.
We can use desk check technique to test logic errors. There are 3 steps to perform desk checking.
First, create a set of test data that includes input and output data.
Second, use the test data to test the coding and record the result.
Lastly, compare the manual results with the computer generated results.

Run-Time Error
 Run-time error is an error that occurs while the program is running or executing.
A run-time error may cause the program to stop running.
 
 DOCUMENTATION PHASE
After this, the programmer will complete the documentation for the program; this includes the user manual, a clear layout of the input and output records and a program listing.

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