C 代码片段:)

#include <stdio.h>

// struct datatype
struct person {
    char name[50];
    int age;
    float salary;
};

// enum datatype
enum color {red, green, blue};

int main() {

    // basic data types
    int a = 10; // 4 bytes
    float b = 5.5; //4 bytes
    char c = 'a'; //1 byte
    double d = 2.3; //8 bytes
    long double e; // 16 bytes (64-bit), 12 bytes (32-bit)
    short integer f; // 2 bytes
    long int g; //8 bytes (64-bit), 4 bytes (32-bit)


    // array
    int arr[5] = {1, 2, 3, 4, 5};

    // pointer
    int *ptr = &a;

    // structure
    struct person person1;
    person1.age = 30;
    person1.salary = 55000.50;

    // enumeration
    enum color mycolor = red;

    // print values
    printf("integer: %d\n", a);
    printf("float: %.2f\n", b);
    printf("character: %c\n", c);
    printf("array: %d\n", arr[0]);
    printf("pointer: %d\n", *ptr);
    printf("structure: name = %s", person1.name);
    printf("enumeration: %d\n", mycolor);
    return 0;
}

#include <stdio.h>

// function prototype with formal parameters
void func(char name[]);

int main() {
    char name[] = "alice";
    //actual parameters
    greet(name);
    return 0;
}

// function definition
void func(char name[]) {
    printf("hello, %s!\n", name);
}

#include <stdio.h>
#include <math.h>

int main() {
    double dividend = 7.5;
    double divisor = 2.0;
    double result;
    int i=2;
    i=i%10;//works on integer types

    result = fmod(dividend, divisor);
    printf("%.1f",result); //for float types

    return 0;
}

#include<stdio.h>
int main()
{
    int x;
    for(x=1; x<=10; x++)
    {
       // ternary conditional operator
       a <= 20 ? (b = 30) : (c = 30);
    }
    return 0;
}

#include<stdio.h>
int main()
{
    int j=1;
    while(j <= 255)
    {
      j++;
    }
    return 0;
}

#define pi 3.14159
#define square(x) ((x) * (x))

#include <stdio.h>
int main() {
    int day = 3;

    switch (day) {
        case 1:
            printf("monday\n");
            break;
        case 2:
            printf("tuesday\n");
            break;
        default:
            printf("invalid day\n");
            break;
    }

    return 0;
}

#include <stdio.h>
#include <stdlib.h>

int main() {
    int *array;
    int size = 5;

    // allocate memory for an array of integers
    array = (int *)malloc(size * sizeof(int));

    // deallocate the memory
    free(array);

    int *a[3];
    a = (int*) malloc(sizeof(int)*3);
    free(a);

    return 0;
}

int *ptr; // declares a pointer to an integer

int x = 10;
int *ptr = &x; // `ptr` now holds the address of `x`

int value = *ptr; // retrieves the value of `x` via `ptr`

#include <stdio.h>

int main() {
    int a = 5;         // normal integer variable
    int *p = &a;       // pointer `p` points to `a`

    printf("value of a: %d\n", a);          // output: 5
    printf("address of a: %p\n", (void*)&a); // output: address of `a`
    printf("value of p: %p\n", (void*)p);   // output: address of `a`
    printf("value pointed to by p: %d\n", *p); // output: 5

    *p = 10; // modifies `a` through the pointer

    printf("new value of a: %d\n", a);      // output: 10

    return 0;
}

int x = 10;
int *ptr = &x;
int **pptr = &ptr; // pointer to pointer

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

// define a structure
struct person {
    char name[50];
    int age;
};

int main() {
    // declare a pointer to a structure
    struct person *ptr;

    // allocate memory for the structure
    ptr = (struct person *)malloc(sizeof(struct person));
    if (ptr == null) {
        printf("memory allocation failed\n");
        return 1;
    }

    // use the arrow operator to access and set structure members
    strcpy(ptr->name, "alice");
    ptr->age = 30;

    // print structure members
    printf("name: %s\n", ptr->name);
    printf("age: %d\n", ptr->age);

    // free allocated memory
    free(ptr);

    return 0;
}

#include <stdio.h>

int main() {
    extern int a;  // accesses a variable from outside
    printf("%d\n", a);
    return 0;
}
int a = 20;

#include <stdio.h>

static int global_var = 10; // global static variable

void display(void) {
    printf("global variable: %d\n", global_var); // accesses global static variable
}

int main(void) {
    display(); // prints 10
    global_var = 20;
    display(); // prints 20
    return 0;
}

#include <stdio.h>

void counter(void) {
    static int count = 0; // local static variable
    count++;
    printf("count: %d\n", count); // prints the current value of count
}

int main(void) {
    counter(); // prints 1
    counter(); // prints 2
    counter(); // prints 3
    return 0;
}

struct book
{
    char name[10];
    float price;
    int pages;
};

typedef unsigned int uint;

int main() {
    uint x = 10;  // equivalent to unsigned int x = 10;
    printf("x = %u\n", x);
    return 0;
}

typedef struct Ntype {
    int i;
    char c;
    long x;
} NewType;