How is C language represented or expressed?

Some common ways to refer to C language are as follows: C is a general-purpose, procedural programming language that can be used to develop various applications.

1. C programming source code: A C program is written in the form of source code, which typically has a file extension of .c or .h. The source code includes the syntax and logic of the C programming language.
2. Preprocessing commands in C: In the C language, preprocessing commands such as #include, #define, can be used to preprocess the source code. These commands allow for macro substitution, file inclusion, and other operations to be performed on the source code before compilation.
3. Compiler commands: C language source code needs to be compiled by a compiler into executable files or library files. Common C language compilers include GCC, Clang, etc. Compiler commands typically include compilation options, source file names, and output file names as parameters.
4. The C Standard Library: C programming language includes a set of standard library functions that can be directly called in a program. These functions provide basic input/output, string manipulation, memory management, and other functionalities.
5. The C language has a set of strict syntax rules which include variable declaration, function definition, and control statements. Following the correct syntax rules ensures the correctness and readability of the program.
6. Characteristics of C language: C language has unique features such as pointers, structures, unions, bit-fields, etc. These features can help programmers better manage memory, handle data, etc.

In conclusion, the C language can be represented and described through source code, preprocessor commands, compiler commands, standard library functions, syntax rules, and features.