Programmers and programming languages

Computer programmers write computer programs that become the components of a computer software product. The finished software product is then distributed by the programmers or by software publishers – companies that specialize in marketing and selling software. Today most businesses and organizations purchase commercial software to avoid the time and expense of writing their own.

Most software provides a task-related environment, which includes a screen display, a means of collecting commands and data from the user, the specifications for processing data, and a method for displaying or outputting data. To create a software environment, a programmer must define properties for each element in the environment, such as where the objects appear, its shape, color and behavior.

A programming language provides the tools a programmer uses to create software and produce a lengthy list of instructions, called source code, which defines the software environment in every detail – what it looks like, how the user enters commands, and how it manipulates data. Most programmers today prefer to use a high-level language, such as C++, Java, Ada, COBOL, or Visual Basic. These languages have some similarities to human languages and produce programs that are fairly easy to test and modify.

A computer’s microprocessor understands only machine language – the instruction set that is “hard wired” within the microprocessor’s circuits. Therefore, instructions written in a high-level language must be translated into machine language before a computer can use them. The process of translating instructions can be accomplished by two special types of programs: compilers and interpreters. A compiler translates all the instructions in a program as a single batch, and the resulting machine language instructions, called object code, are placed in a new file. Most of the program files on a distribution CD for commercial software are compiled so that they contain machine language instructions that are ready for the processor to execute. As an alternative to a compiler, an interpreter converts one instruction at a time while the program is running. An interpreter reads the first instruction, converts it into machine language, and then sends it to the microprocessor. After the instruction is executed, the interpreter converts the next instruction, and so on.

Software is categorized as application software or system software. The primary purpose of application software is to help people carry out tasks using a computer. In contrast, the primary purpose of system software – your computer’s operating system, device drivers, programming languages, and utilities – is to help the computer to carry out its basic operating functions.

Software can be classified into categories (see fig. 3):

Fig. 3: Software categories

Comprehension check. Mark the following statements as True or False.

1. Computer software typically consists of many files that contain user-executable programs, support programs and data files.

2. The main executable file provides the primary set of instructions for the computer to execute and calls various support programs and data files as needed.

3. Support programs often have file extensions such as.txt,.bmp, and.hlp.

4. Individuals often write software for their personal computers.

5. High-level languages are fairly easy to test and modify.

6. A compiler converts high-level instructions into a new file containing machine language instructions.

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