HP-UX HB v13.00 Ch-11 - Software Development

HP-UX Handbook – Rev 13.00 Page 5 (of 101)

Chapter 11 Software Development

October 29, 2013

By default, the front-ends will execute all necessary build steps to create an executable from the

input files passed to it. In the simplest case the build command to create a program from a source

file is:

To execute only one step of the build process, additional arguments must be passed to the

frontend. Which options are available and much other information about the frontend and the

compiler itself can be found in the appropriate frontend manpages which are installed with the

compiler product.

Source Code

This page is intended to give a somewhat simplified view over the structure of programs and its

sources. The things discussed will be demonstrated with little pieces of ANSI C code, which

hopefully can be understood even without programming knowhow.

Program Structure

Programs are organized in functions. A function is (as you might remember from your math

classes) a construct that takes one or more operands, and returns a result. In a program functions

are also referenced to as procedures, subroutines or methods, the operands are called arguments

or parameters, and the result is usually called the return value. The function body contains the

instructions that process the arguments to generate the return value. Often the major task of a

function is to process the arguments rather than generating a return value. The instructions can

also contain calls to other functions to execute subtasks.

A program is intended to process data, so besides functions it also needs means to store data. A

piece of data is called a variable.

Functions and variables are often abstractly called symbols. Symbols are only distinguished by

name. We decide between global and local symbols. As the name implies, global symbols can be

accessed in the whole program, while local symbols are only available within a certain area of

the program. This access range is called the scope of the variable.

Programmatical Conventions

In a program source you typically will find declarations and definitions for symbols. A

declaration is used to specify names and types of functions, function arguments, return values

and variables. It determines how to use a symbol so it can be referenced, but it doesn't create it.

int main();