c语言

/*
 * @Author: huanjiang-lab vibration@zju.edu.cn
 * @Date: 2023-11-10 13:51:34
 * @LastEditors: huanjiang-lab vibration@zju.edu.cn
 * @LastEditTime: 2023-11-27 09:19:51
 * @FilePath: \c-learn\zhizhen.c
 * @Description: 这是默认设置,请设置`customMade`, 打开koroFileHeader查看配置 进行设置: https://github.com/OBKoro1/koro1FileHeader/wiki/%E9%85%8D%E7%BD%AE
 */
// C program to demonstrate that we can change
// local values of one function in another using pointers.

#include <stdio.h>
#define MAX 10

void swap(int *x, int *y)
{
    int temp;
    temp = *x;
    *x = *y;
    *y = temp;
}

void fun(int *height, int *age)
{
    int n = 10;
    *height = n * 10;
    *age = n * 2000;
}

int *createArray(int size)
{
    int i;
    int *arr = (int *)(malloc(sizeof(int) * size));
    for (i = 0; i < size; i++)
    {
        arr[i] = i * i;
    }
    return arr;
}

int *sumArray(int arr)
{
    return 0;
}

int add(int x, int y)
{
    return x + y;
}

int substract(int x, int y)
{
    return x - y;
}

int multiply(int x, int y)
{
    return x * y;
}

int divide(int x, int y)
{
    return x / y;
}

int module(int x, int y)
{
    return x % y;
}

int sum2DArray(int **arr, int *start, int *end)
{
    int sum = 0;
    // int *p = *arr;
    int *p = NULL;
    p = start;
    while (p < end)
    {
        sum += *p;
        p++;
    }
    return sum;
}

typedef int (*operation_fun)(int, int);

void main()
{
    int num = 0;
    int (*ptr_add)(int, int) = add;
    void (*ptr_swap)(int, int) = swap;

    int a = 100, b = 200;
    int sum = ptr_add(a, b);
    ptr_swap(&a, &b);
    printf("the result is %d\n", sum);
    printf("after swap a is %d,b is %d\n", a, b);

    operation_fun operations[] = {
        &add,
        &substract,
        &multiply,
        &divide,
        &module};

    // int (*operations[])(int, int) = {add, substract, multiply, divide, module};
    // int (*operations[])(int, int) = {&add, &substract, &multiply, &divide, &module};

    char *arr[] = {"add", "substract", "multiply", "divide", "module"};

    int result = 0;
    int i, j;
    for (i = 0; i < 5; i++)
    {
        result = operations[i](10, 20);
        printf("%s of two number result is %d\n", arr[i], result);
    }

    int arr1[3][4] = {0};
    int arr2[3][4] = {0};
    int arr3[3][4] = {0};
    for (i = 0; i < 3; i++)
    {
        for (j = 0; j < 4; j++)
        {
            arr1[i][j] = i + j;
            arr2[i][j] = i - j;
            arr3[i][j] = i * j;
        }
    }
    int *ptr_arr_start = &arr2;
    int *ptr_arr_end = &arr2 + 1;
    sum = sum2DArray(arr2, ptr_arr_start, ptr_arr_end);

    // int a = 100, b = 200;
    // printf("before swap a is %d, b is %d\n", a, b);
    // swap(&a, &b);
    // printf("after swap a is %d, b is %d\n", a, b);
    // int p_height;
    // int p_age;
    // int *p_arr = createArray(MAX);
    // int i;
    // fun(&p_height, &p_age);
    // printf("height is %d and age is %d\n", p_height, p_age);
    // for (i = 0; i < MAX; i++)
    // {
    //     printf("%d\n", p_arr[i]);
    // }

    // int c = 30;
    // int *ptr1 = &c;
    // int **ptr2 = &ptr1;

    // printf("c is %d\n", c);
    // printf("ptr1 is %d\n", *ptr1);
    // printf("ptr2 is %d\n", **ptr2);
}