STEPS FOR DEVELOPING A ‘C’ PROGRAM.

BYSAHITHI NARAPARAJU

INTRODUCTION• The program development process in C includes three

important stages namely:

1) Program design

2) Program coding and

3) Program testing

• All the three stages contribute to production of high quality programs

1) Program design :

• It is a foundation for good program.

• Program design basically concerned with development strategy to be used in writing program, in order to achieve solution of a problem.

• This includes mapping out a solution procedure and the form the program would take.

• Program design involves 4 stages namely:

i) Problem analysis

ii) Outlining the program structure

iii) Algorithm development

iv) Selection of control structure

• Problem analysis: Before we think a solution procedure to a problem, we must fully understand the nature of the problem and what we want the program to do.

• Outlining the program structure : Once we have decided what we want and what we have, the next step is to decide how to do it.

• As a structured language C lends itself to top-down approach.

• Top-down approach means decomposing of solution procedure into tasks that form a hierarchical structure.

• The essence of top-down approach is to cut the whole program into number of independent constitutent tasks and then cut into smaller subtasks

• This approach will produce a readable and modular code that can be easily understood and maintained.

• It also helps us classify overall functioning of a program in terms of lower- level functions.

iii) Algorithm Development: Step by step procedure for each function is known as algorithm.

• The most common method of describing an algorithm is through the use of flow charts.

• The other method is pseudo code.

• flow chart represents algorithm pictorially, while pseudo code describe the solution steps in logical order.

iv) Control structures: Any algorithm can be structured using three basic control structure namely:

a) sequence structure b) selection structure

c) looping structure

a) Sequence structure: sequence structure denotes the execution of statements sequentially one after another.

b) Selection structure: selection structure involves a decision , based on a condition and may have 2 or more branches

Eg: if else and switch statements.

c) Looping structure: looping structure is used when a set of instructions is evaluated repeatedly.

Eg: do, while, for statements.

• A well designed program will provide following benefits:

1) Coding is easy and error-free.

2) Testing is simple.

3) Maintence is easy

4) Good documentation is possible.

5) Cost estimates can be made more accurately.

6) Progress of coding may be controlled more precisely.

• 2) Program coding : progrm coding should be readable and simple to understand.

• Complex logic and tricky coding should be avoided.

• The elements of coding include:

i) Internal documentation

ii) Construction of statements

iii) Generality of program

iv) Input/Output formats

3) Program testing: Testing is the process of reviewing and executing a program with the intent of detecting errors.

• The compiler can detect syntactic and semantic errors, it cannot detect run-time and logical errors that show up during execution of program.

• Testing should include necessary steps to detect all possible errors in the program.

• Testing process may include following 2 stages:

i) Human testing andii) Computer-based testing.

a) Human testing : It is an effective error-detection

Process and is done before the computer based testing begins.

• Human testing methods include code inspection by programmer, code inspection by test group and review by peer group.

• The test is carried out statement by statement and is analyzed with respect to check list of common programming errors.

• In addition to finding errors, the programming style and choice of algorithm are reviewed.

b) Computer-based testing: computer based testing involves two stages namely:

i) Compiler testing and ii) Run-time testing• Compiler testing is the simplest of two and

detects undiscovered syntax errors.• The program executes when compiler

detects no more errors.• Run-time errors may produce run-time error

messages such as “null-pointer assignments” “stack overflow”.

• When program is free from all such errors, it produces output.