Steps to develop a computer program

A program is developed in a series of steps called the program development life cycle.

 Problem definition
        |
 Analysis --> Design (algorithm, flowchart)
        |
 Coding --> Compile / Test / Debug
        |
 Documentation --> Maintenance

1. Problem definition: understand clearly what the problem is and what is required.
2. Analysis: identify inputs, outputs, processing needed, and constraints.
3. Design: plan the solution using an algorithm, pseudo-code or flowchart, before writing any code.
4. Coding: write the program in a suitable programming language following its syntax.
5. Compilation: the compiler reports syntax errors, which the programmer corrects; then the linker creates the executable.
6. Testing and debugging: run with sample data to find logical and runtime errors, and correct them.
7. Documentation: write comments, user manual and technical description.
8. Maintenance: update the program for new needs and fix errors found later.

Example: to find the area of a circle, the input is the radius, the output is the area, the process is area = 3.14 * r * r; this is converted into an algorithm, coded in C, tested with r = 2 (area 12.56) and documented.