what is c compiler

C compiler, also known as C language compiler, refers to a translation program that translates a source program written in C language into an equivalent target program in machine language format. The c compiler will first check the correctness of the source program and decompose it into a number of basic components; then create corresponding equivalent target program parts based on these basic components.

The operating environment of this tutorial: windows7 system, c99 version, Dell G3 computer.

c compiler is a set of software provided by computer manufacturers. A C compiler, also known as a C language compiler, refers to a translation program that translates a source program written in C language into an equivalent target program in machine language format.

The compiler is a translation program implemented using a generative implementation approach. It takes a source program written in a high-level programming language as input, and a target program expressed in assembly language or machine language as output. The compiled target program usually also goes through a running stage in order to run with the support of the running program, process the initial data, and calculate the required calculation results.

The basic function of the compiler is to translate the source program (high-level language) into the target program. However, as a compilation system with practical application value, in addition to basic functions, it should also have important functions such as syntax checking, debugging measures, modification methods, coverage processing, target program optimization, use of different languages, and human-computer contact.

• ① Grammar check: Check whether the source program is grammatical. If it is not grammatical, the compiler should point out the location, nature and relevant information of the grammatical error. The compiled program should enable the user to detect as many errors as possible in one go.

• ②Debugging measures: Check whether the source program meets the designer's intention. To this end, the compiler is required to place some output instructions in the compiled target program so that information about the dynamic execution of the program can be output when the target program is running, such as changes in variable values, circuits experienced during program execution, etc. This information helps users verify and verify whether the source program expresses the algorithm requirements.

• ③Modification means: Provide users with a simple means to modify the source program. Compilers usually provide batch modification means (used to modify a large number of errors that are temporarily difficult to modify) and on-site modification means (used to modify a small number of errors that are temporarily easy to modify during runtime).

• ④ Coverage processing: It is mainly set up to handle large-scale problem programs with long programs and large amounts of data. The basic idea is to let some program segments and data share certain storage areas, in which only the programs or data that are currently used are stored; the remaining programs and data that are not used temporarily are first stored in auxiliary storage such as disks, and can be dynamically transferred when needed. .

• ⑤ Target program optimization: Improve the quality of the target program, that is, it takes up less storage space and the program’s running time is short. Depending on the optimization goals, the compiler can choose to implement expression optimization, loop optimization, or global program optimization. Some target program optimization is performed at the source program level, and some is performed at the target program level.

• ⑥Using different languages: Its function helps users write applications using multiple programming languages ​​or apply existing program modules written in different languages. The most common is the combination of high-level language and assembly language. This can not only make up for the difficulty of high-level languages ​​in expressing certain non-numeric processing operations or direct control and access to peripheral devices and hardware registers, but also facilitates writing core programs in assembly language to improve operating efficiency.

• ⑦ Man-machine connection: Achieve well-designed functions when determining the compiler implementation plan. The purpose is to facilitate users to understand the internal working conditions in a timely manner during the compilation and running stages, and to effectively supervise and control the operation of the system.

The implementation plan of the early compiler was to completely incorporate the above functions into the compiler. However, the common practice is to configure debuggers, editors, and connection assemblers with the support of the operating system to assist in debugging, modifying, overwriting, and combining functions in different languages. However, when designing a compiler, careful consideration must be given to issues such as how to interface with these subsystems.

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