The basic units of C language and their functions

C language is a programming language widely used in system programming and application development. In the C language, there are some basic units that programmers often come into contact with when writing programs. Mastering these basic units is very important for mastering the C language. This article will introduce the basic units in C language and their functions in detail, and provide specific code examples to help readers better understand.

1. Keywords (Keywords) :
   Keywords in C language are defined in advance by the compiler, have special meanings, and cannot be used by programmers as Identifier usage. For example: int, char, if, for, etc. The following is a simple code example:

   #include <stdio.h>
   
   int main() {
       int a = 10;
       char b = 'A';
   
       if (a > 5) {
           printf("a大于5
   ");
       }
   
       for (int i = 0; i < 5; i++) {
           printf("i的值：%d
   ", i);
       }
   
       return 0;
   }

2. Identifiers:
   Identifiers are defined by programmers to identify variables, Functions, arrays, etc. Identifiers can be composed of letters, numbers, and underscores, but must begin with a letter or an underscore. The following is an example:

   #include <stdio.h>
   
   int main() {
       int num = 10;
       printf("num的值：%d
   ", num);
   
       return 0;
   }

3. Data Types:
   There are some basic data types in C language, such as integer and character , floating point type, etc. The following is an example:

   #include <stdio.h>
   
   int main() {
       int integerNum = 10;
       char charVar = 'A';
       float floatNum = 3.14;
   
       printf("整型变量：%d
   ", integerNum);
       printf("字符型变量：%c
   ", charVar);
       printf("浮点型变量：%f
   ", floatNum);
   
       return 0;
   }

4. Operators:
   There are various operators in C language, such as assignment operators and arithmetic operators , logical operators, etc. The following is an example:

   #include <stdio.h>
   
   int main() {
       int a = 10;
       int b = 20;
       int sum = a + b;
       int product = a * b;
   
       printf("和：%d
   ", sum);
       printf("积：%d
   ", product);
   
       return 0;
   }

5. Control Flow Statements:
   Control flow statements in C language include if statements, for loops, while loops, etc., are used to control the execution flow of the program. The following is an example:

   #include <stdio.h>
   
   int main() {
       int num = 10;
   
       if (num > 5) {
           printf("num大于5
   ");
       } else {
           printf("num小于等于5
   ");
       }
   
       for (int i = 0; i < 5; i++) {
           printf("i的值：%d
   ", i);
       }
   
       return 0;
   }

By learning the basic units and their functions in C language, it can help readers better understand the core concepts of C language and improve the efficiency and quality of program writing. . I hope the content of this article will be helpful to readers.

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