c program is made up of header files, macro definitions, global and static variables, functions, comments, statements, compound statements, flow control, process control, data types, library functions and so on.
1, the header file: contains a variety of preprocessing instructions needed in the program, such as #include<; stdio.h>;, #include<; stdlib.h>;; etc., as well as function prototype declarations, such as int main (void), void print_ string (char*str), etc.
2, macro definition: used to name constants, such as #define PI3.14159, can also be used to define function macros, such as #define SQUARE (X) ((X)*(X)).
3. Global and static variables: global variables are visible throughout the program, while static variables are visible only in the file in which they are defined.
4, function: the basic unit of the C program, each function has its own function, such as the main function main (), the output function printf () and so on.
5, comments: used to explain the function and role of the code, improve the readability of the code, divided into single-line comments and multi-line comments. Single-line comments with / /, multi-line comments with / ** /.
6, statements: the program to perform the command, including expressions, empty statements, function call statements, control statements and so on.
7, compound statement: a collection of statements surrounded by a pair of curly braces {}, such as if (a & lt;; b) {printf ("a is less than b"); return0; }.
8, flow control: control the program execution order of statements, such as if.... .else, while, do... . while, for, and so on.
9, data types: data types in C include basic types, constructive types, pointer types, null types and so on.
10, library functions: functions provided by the C standard library, such as printf (), scanf (), getchar (), putchar () and so on.
Practical applications of c program:
1, system software: C language is widely used to develop system software, such as operating systems, compilers, database management systems. This is because C provides direct access to hardware and also memory management, making it suitable for such complex and precise control.
2. Embedded systems: In embedded systems, C language is also widely used. For example, the development of microcontrollers, DSPs and other embedded hardware control programs for a variety of practical applications.
3, game development: many large games and applications are written in C or C++. This is because C and C++ provide more direct memory access and better performance control.
4. Real-time systems: C is also common in real-time systems development, such as in industrial automation and aerospace. This is because C runs efficiently and interacts directly with the hardware.
5, safety-critical applications: C is also often used in safety-critical applications, such as aerospace, medical devices, and industrial process control. This is because the rigor and clear semantics of the C language make it more suitable for such environments that have a very low tolerance for errors.