19-09-2012, 12:36 PM
Software
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Software is the collection of computer programs and related data that provide the instructions telling a computer what to do. We can also say software refers to one or more computer programs and data held in the storage of the computer for some purposes.
Types of software
Programming software
Programming software usually provides tools to assist a programmer in writing computer programs, and software using different programming languages in a more convenient way. The tools include:
• Compilers
A compiler is a computer program (or set of programs) that transforms source code written in a programming language (the source language) into another computer language (the target language, often having a binary form known as object code). The most common reason for wanting to transform source code is to create an executable program.
The name "compiler" is primarily used for programs that translate source code from a high-level programming language to a lower level language (e.g., assembly language or machine code). If the compiled program can only run on a computer whose CPU or operating system is different from the one on which the compiler runs the compiler is known as a cross-compiler. A program that translates from a low level language to a higher level one is a decompiler. A program that translates between high-level languages is usually called a language translator, source to source translator, or language converter. A language rewriter is usually a program that translates the form of expressions without a change of language.
High-level programming language
A high-level programming language is a programming language with strong abstraction from the details of the computer. In comparison to low-level programming languages, it may use natural language elements, be easier to use, or be more portable across platforms. Such languages hide the details of CPU operations such as memory access models and management of scope.
This greater abstraction and hiding of details is generally intended to make the language user-friendly, as it includes concepts from the problem domain instead of those of the machine used. A high-level language isolates the execution semantics of computer architecture from the specification of the program, making the process of developing a program simpler and more understandable with respect to a low-level language. The amount of abstraction provided defines how "high-level" a programming language is.
The first high-level programming languages were designed in the 1950s. Now there are dozens of different languages, including Ada, Algol, BASIC, COBOL, FORTRAN, LISP, Pascal, and Prolog.
Low-level programming language
In computer science, a low-level programming language is a programming language that provides little or no abstraction from a computer's instruction set architecture. A low-level language does not need a compiler or interpreter to run; the processor for which the language was written is able to run the code without using either of these.
Low-level programming languages are sometimes divided into two categories: first generation, and second generation.
History of C Language
C is a general-purpose computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system
C is one of the most popular programming languages of all time[5][6] and there are very few computer architectures for which a C compiler does not exist. C has greatly influenced many other popular programming languages, most notably C++, which began as an extension to C.
Design
C is an imperative (procedural) systems implementation language. It was designed to be compiled using a relatively straightforward compiler, to provide low-level access to memory, to provide language constructs that map efficiently to machine instructions, and to require minimal run-time support. C was therefore useful for many applications that had formerly been coded in assembly language.
Minimalism
C's design is tied to its intended use as a portable systems implementation language. It provides simple, direct access to any addressable object (for example, memory-mapped device control registers), and its source-code expressions can be translated in a straightforward manner to primitive machine operations in the executable code.
Characteristics
C exhibits the following more specific characteristics:
• Variables may be hidden in nested blocks
• Partially weak typing; for instance, characters can be used as integers
• Low-level access to computer memory by converting machine addresses to typed pointers
• Function and data pointers supporting ad hoc run-time polymorphism
• array indexing as a secondary notion, defined in terms of pointer arithmetic
• A preprocessor for macro definition, source code file inclusion, and conditional compilation
• Complex functionality such as I/O, string manipulation, and mathematical functions consistently delegated to library routines
• A relatively small set of reserved keywords
[attachment=34047]
Software is the collection of computer programs and related data that provide the instructions telling a computer what to do. We can also say software refers to one or more computer programs and data held in the storage of the computer for some purposes.
Types of software
Programming software
Programming software usually provides tools to assist a programmer in writing computer programs, and software using different programming languages in a more convenient way. The tools include:
• Compilers
A compiler is a computer program (or set of programs) that transforms source code written in a programming language (the source language) into another computer language (the target language, often having a binary form known as object code). The most common reason for wanting to transform source code is to create an executable program.
The name "compiler" is primarily used for programs that translate source code from a high-level programming language to a lower level language (e.g., assembly language or machine code). If the compiled program can only run on a computer whose CPU or operating system is different from the one on which the compiler runs the compiler is known as a cross-compiler. A program that translates from a low level language to a higher level one is a decompiler. A program that translates between high-level languages is usually called a language translator, source to source translator, or language converter. A language rewriter is usually a program that translates the form of expressions without a change of language.
High-level programming language
A high-level programming language is a programming language with strong abstraction from the details of the computer. In comparison to low-level programming languages, it may use natural language elements, be easier to use, or be more portable across platforms. Such languages hide the details of CPU operations such as memory access models and management of scope.
This greater abstraction and hiding of details is generally intended to make the language user-friendly, as it includes concepts from the problem domain instead of those of the machine used. A high-level language isolates the execution semantics of computer architecture from the specification of the program, making the process of developing a program simpler and more understandable with respect to a low-level language. The amount of abstraction provided defines how "high-level" a programming language is.
The first high-level programming languages were designed in the 1950s. Now there are dozens of different languages, including Ada, Algol, BASIC, COBOL, FORTRAN, LISP, Pascal, and Prolog.
Low-level programming language
In computer science, a low-level programming language is a programming language that provides little or no abstraction from a computer's instruction set architecture. A low-level language does not need a compiler or interpreter to run; the processor for which the language was written is able to run the code without using either of these.
Low-level programming languages are sometimes divided into two categories: first generation, and second generation.
History of C Language
C is a general-purpose computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system
C is one of the most popular programming languages of all time[5][6] and there are very few computer architectures for which a C compiler does not exist. C has greatly influenced many other popular programming languages, most notably C++, which began as an extension to C.
Design
C is an imperative (procedural) systems implementation language. It was designed to be compiled using a relatively straightforward compiler, to provide low-level access to memory, to provide language constructs that map efficiently to machine instructions, and to require minimal run-time support. C was therefore useful for many applications that had formerly been coded in assembly language.
Minimalism
C's design is tied to its intended use as a portable systems implementation language. It provides simple, direct access to any addressable object (for example, memory-mapped device control registers), and its source-code expressions can be translated in a straightforward manner to primitive machine operations in the executable code.
Characteristics
C exhibits the following more specific characteristics:
• Variables may be hidden in nested blocks
• Partially weak typing; for instance, characters can be used as integers
• Low-level access to computer memory by converting machine addresses to typed pointers
• Function and data pointers supporting ad hoc run-time polymorphism
• array indexing as a secondary notion, defined in terms of pointer arithmetic
• A preprocessor for macro definition, source code file inclusion, and conditional compilation
• Complex functionality such as I/O, string manipulation, and mathematical functions consistently delegated to library routines
• A relatively small set of reserved keywords