cpp/base/README.md

使用GPT 3.5 学习C语言: 25个简单代码让你了解 C 语言基本语法

以下是一些学习C语言的常用代码示例，涵盖了各种语法和概念：

1. Hello World

   #include

   int main() { printf("Hello, World!\n"); return 0; }

2. 变量和数据类型

   #include

   int main() { int age = 20; float weight = 65.5; char grade = 'A'; printf("Age: %d\n", age); printf("Weight: %.2f\n", weight); printf("Grade: %c\n", grade); return 0; }

3. 输入输出

   #include

   int main() { int num; printf("Enter a number: "); scanf("%d", &num); printf("You entered: %d\n", num); return 0; }

4. 条件语句

   #include

   int main() { int num; printf("Enter a number: "); scanf("%d", &num); if (num > 0) {

   printf("Positive number\n");
   

   } else if (num < 0) {

   printf("Negative number\n");
   

   } else {

   printf("Zero\n");
   

   } return 0; }

5. 循环语句

   #include

   int main() { int i; for (i = 1; i <= 5; i++) {

   printf("%d ", i);
   

   } printf("\n");

   int j = 1; while (j <= 5) {

   printf("%d ", j);
   j++;
   

   } printf("\n");

   int k = 1; do {

   printf("%d ", k);
   k++;
   

   } while (k <= 5); printf("\n");

   return 0; }

6. 数组

   #include

   int main() { int numbers[5] = {1, 2, 3, 4, 5}; printf("First element: %d\n", numbers[0]); printf("Second element: %d\n", numbers[1]);

   int i; for (i = 0; i < 5; i++) {

   printf("%d ", numbers[i]);
   

   } printf("\n");

   return 0; }

希望以上代码示例能帮助你学习C语言的基础知识。请注意，这只是一小部分C语言的语法示例，还有很多其他的语法和概念等待你去探索和学习。

当然，以下是更多的C语言代码示例，涵盖了更多的语法和概念：

1. 函数

   #include

   int add(int a, int b) { return a + b; }

   int main() { int result = add(2, 3); printf("Result: %d\n", result); return 0; }

2. 字符串

   #include

   int main() { char name[20] = "John Doe"; printf("Name: %s\n", name);

   char message[50]; printf("Enter a message: "); fgets(message, sizeof(message), stdin); printf("You entered: %s\n", message);

   return 0; }

3. 结构体

   #include

   typedef struct { char name[20]; int age; } Person;

   int main() { Person person; strcpy(person.name, "John Doe"); person.age = 25;

   printf("Name: %s\n", person.name); printf("Age: %d\n", person.age);

   return 0; }

4. 指针

   #include

   int main() { int num = 10; int *ptr = #

   printf("Value: %d\n", num); printf("Address: %p\n", &num); printf("Pointer value: %p\n", ptr); printf("Dereference pointer: %d\n", *ptr);

   return 0; }

5. 文件操作

   #include

   int main() { FILE *file = fopen("file.txt", "w"); if (file != NULL) {

   fprintf(file, "This is some text.");
   fclose(file);
   printf("File created and written successfully.\n");
   

   } else {

   printf("Error opening file.\n");
   

   }

   return 0; }

以上示例涵盖了C语言中的一些常用语法和概念，希望对你的学习有所帮助。记得不断练习和探索，以加深对C语言的理解和掌握。

当然，以下是更多的C语言代码示例，涵盖了更多的语法和概念：

1. 动态内存分配

   #include #include

   int main() { int *numbers = (int *)malloc(5 * sizeof(int)); if (numbers != NULL) {

   numbers[0] = 1;
   numbers[1] = 2;
   numbers[2] = 3;
   numbers[3] = 4;
   numbers[4] = 5;
   
   int i;
   for (i = 0; i < 5; i++) {
       printf("%d ", numbers[i]);
   }
   
   free(numbers);
   

   } else {

   printf("Memory allocation failed.\n");
   

   }

   return 0; }

2. 枚举

   #include

   typedef enum { MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY } Day;

   int main() { Day today = TUESDAY;

   switch (today) {

   case MONDAY:
       printf("It's Monday.\n");
       break;
   case TUESDAY:
       printf("It's Tuesday.\n");
       break;
   case WEDNESDAY:
       printf("It's Wednesday.\n");
       break;
   case THURSDAY:
       printf("It's Thursday.\n");
       break;
   case FRIDAY:
       printf("It's Friday.\n");
       break;
   case SATURDAY:
       printf("It's Saturday.\n");
       break;
   case SUNDAY:
       printf("It's Sunday.\n");
       break;
   

   }

   return 0; }

3. 递归

   #include

   int factorial(int n) { if (n <= 1) {

   return 1;
   

   } else {

   return n * factorial(n - 1);
   

   } }

   int main() { int num = 5; int result = factorial(num); printf("Factorial of %d is %d.\n", num, result);

   return 0; }

4. 多文件编程

file1.c:

#include <stdio.h>

void sayHello() {
printf("Hello from file1.c!\n");
}

file2.c:

#include <stdio.h>

void sayHello(); // 函数声明

int main() {
sayHello();
return 0;
}

编译和链接两个文件：

gcc file1.c file2.c -o program

以上示例涵盖了C语言中的更多语法和概念，希望对你的学习有所帮助。记得不断练习和探索，以加深对C语言的理解和掌握。

当然，以下是更多的C语言代码示例，涵盖了更多的语法和概念：

1. 链表

   #include #include

   typedef struct Node { int data; struct Node *next; } Node;

   void insert(Node **head, int data) { Node *newNode = (Node *)malloc(sizeof(Node)); newNode->data = data; newNode->next = NULL;

   if (*head == NULL) {

   *head = newNode;
   

   } else {

   Node *temp = *head;
   while (temp->next != NULL) {
       temp = temp->next;
   }
   temp->next = newNode;
   

   } }

   void display(Node *head) { Node *temp = head; while (temp != NULL) {

   printf("%d ", temp->data);
   temp = temp->next;
   

   } printf("\n"); }

   int main() { Node *head = NULL; insert(&head, 1); insert(&head, 2); insert(&head, 3); display(head);

   return 0; }

2. 函数指针

   #include

   int add(int a, int b) { return a + b; }

   int subtract(int a, int b) { return a - b; }

   int main() { int (*ptr)(int, int);

   ptr = add; printf("Addition: %d\n", ptr(2, 3));

   ptr = subtract; printf("Subtraction: %d\n", ptr(5, 3));

   return 0; }

3. 位运算

   #include

   int main() { unsigned int a = 5; // 0000 0101 unsigned int b = 3; // 0000 0011

   unsigned int result;

   result = a & b; // 0000 0001 (位与) printf("Bitwise AND: %u\n", result);

   result = a | b; // 0000 0111 (位或) printf("Bitwise OR: %u\n", result);

   result = a ^ b; // 0000 0110 (位异或) printf("Bitwise XOR: %u\n", result);

   result = ~a; // 1111 1010 (位取反) printf("Bitwise NOT: %u\n", result);

   result = a << 2; // 0001 0100 (左移) printf("Left Shift: %u\n", result);

   result = a >> 1; // 0000 0010 (右移) printf("Right Shift: %u\n", result);

   return 0; }

4. 宏定义

   #include

   #define PI 3.14159 #define SQUARE(x) ((x) * (x))

   int main() { float radius = 2.5; float area = PI * SQUARE(radius);

   printf("Area: %.2f\n", area);

   return 0; }

5. 错误处理

   #include #include #include

   int main() { FILE *file = fopen("nonexistent.txt", "r"); if (file == NULL) {

   printf("Error opening file: %s\n", strerror(errno));
   

   } else {

   // 文件操作
   fclose(file);
   

   }

   return 0; }

   以上示例涵盖了C语言中的更多语法和概念，希望对你的学习有所帮助。记得不断练习和探索，以加深对C语言的理解和掌握。

   当然，以下是更多的C语言代码示例，涵盖了更多的语法和概念：

   1. 位字段

      #include

      struct Flags { unsigned int isRed : 1; unsigned int isGreen : 1; unsigned int isBlue : 1; };

      int main() { struct Flags f; f.isRed = 1; f.isGreen = 0; f.isBlue = 1;

      printf("Red: %u\n", f.isRed); printf("Green: %u\n", f.isGreen); printf("Blue: %u\n", f.isBlue);

      return 0; }

   2. 类型转换

      #include

      int main() { int a = 10; double b = 3.14;

      double result = (double)a + b;

      printf("Result: %.2f\n", result);

      return 0; }

   3. 函数参数默认值

      #include

      void greet(char *name, char *message) { if (name == NULL) {

      name = "Guest";
      

      } printf("Hello, %s! %s\n", name, message); }

      int main() { greet(NULL, "Welcome to the program."); greet("John", "Nice to meet you.");

      return 0; }

   4. 结构体指针与箭头操作符

      #include #include

      typedef struct { int x; int y; } Point;

      int main() { Point *p = (Point *)malloc(sizeof(Point)); p->x = 2; p->y = 3;

      printf("x: %d\n", p->x); printf("y: %d\n", p->y);

      free(p);

      return 0; }

   5. 逗号运算符

      #include

      int main() { int a = 2, b = 3, c = 4, result;

      result = (a * b) + (c - a), a++, b++, c++;

      printf("Result: %d\n", result); printf("a: %d\n", a); printf("b: %d\n", b); printf("c: %d\n", c);

      return 0; }

   以上示例涵盖了C语言中的更多语法和概念，希望对你的学习有所帮助。记得不断练习和探索，以加深对C语言的理解和掌握。