High and low level languages.

High and low level languages.

What is a computer program?
A computer program is a collection of instructions that can be executed by a computer to perform a specific task.

High level language.
A high-level language (HLL) is a programming language such as C, FORTRAN, or Pascal that enables a programmer to write programs that are more or less independent of a particular type of computer. Such languages are considered high-level because they are closer to human languages and further from machine languages.

Examples.
Python, Visual Basic, Delphi, Perl, PHP, ECMAScript, Ruby, C#, Java.

Features and advantages.

• Require translation.
• Portable.
• Easier to read, write and maintain as commands are similar to English.
• Allow access to module libraries.
• Use data types and data structures, selection statements and repetition/iteration constructs.
• Use logic operators and functions that are built into the language.

Disadvantages.

• It takes additional translation times to translate the source to machine code.
• High level programs are comparatively slower than low level programs.
• Compared to low level programs, they are generally less memory efficient.
• Cannot communicate directly with the hardware.

Low level languages.

A low-level programming language is a programming language that provides little or no abstraction from a computer's instruction set architecture—commands or functions in the language map closely to processor instructions. Generally, this refers to either machine code or assembly language.

Examples.

IBM 360 assembler, PDP-10 assembler, Intel x86 assembler.

Advantages.

• Programs developed using low level languages are fast and memory efficient.
• Programmers can utilize processor and memory in better way using a low level language.
• There is no need of any compiler or interpreters to translate the source to machine code. Thus, cuts the compilation and interpretation time.
• Low level languages provide direct manipulation of computer registers and storage.
• It can directly communicate with hardware devices.

Disadvantages.

• Programs developed using low level languages are machine dependent and are not portable.
• It is difficult to develop, debug and maintain.
• Low level programs are more error prone.
• Low level programming usually results in poor programming productivity.
• Programmer must have additional knowledge of the computer architecture of particular machine, for programming in low level language.