test_2_27（C指针）

test_2_27

#define _CRT_SECURE_NO_WARNINGS 1#include <stdio.h>使用指针数组来模拟实现二维数组int main()
{int* arr[10];//指针数组int arr1[] = { 1,2,3,4,5 };int arr2[] = { 2,3,4,5,6 };int arr3[] = { 3,4,5,6,7 };int* arr[3] = {arr1, arr2, arr3};int i = 0;for (i = 0; i < 3; i++){int j = 0;for (j = 0; j < 5; j++){printf("%d ", arr[i][j]);}printf("\n");}return 0;
}int main()
{char ch = 'w';char* pc = &ch;printf("%c\n", *pc);*pc = 'q';printf("%c\n", ch);return 0;
}int main()
{int a = 20;a = 200;3 = 5;const char * p = "hello world";printf("%c\n", *p);*p = 'q';//errreturn 0;
}#include <string.h>int main()
{const char* p = "hello world";printf("%s\n", p);printf("%s\n", "hello world");int len = strlen(p);int i = 0;for (i = 0; i < len; i++){printf("%c", *(p + i));}return 0;
}int main()
{char arr[] = "abcdef";char* p = arr;printf("%s\n", arr);printf("%s\n", p);return 0;
}#include <stdio.h>int main()
{char str1[] = "hello bit.";char str2[] = "hello bit.";const char* str3 = "hello bit.";const char* str4 = "hello bit.";if (str1 == str2)printf("str1 and str2 are same\n");//1elseprintf("str1 and str2 are not same\n");//2if (str3 == str4)printf("str3 and str4 are same\n");//3elseprintf("str3 and str4 are not same\n");//4return 0;
}int main()
{int * p;int* * pp;int arr[10] = {0};int (*p)[10] = &arr;//取出的是数组的地址p应该是数组指针,p指向的是数组，数组10个元素，每个元素的类型是intreturn 0;
}int main()
{int* ptr;char arr[5];char (*p)[5] = &arr;//p是数组指针char (*)[5] 是数组指针类型char* arr[5];char* (*p)[5] = &arr;return 0;
}int main()
{int arr[10] = { 1,2,3,4,5,6,7,8,9,10 };int* p = arr;int i = 0;int sz = sizeof(arr) / sizeof(arr[0]);for (i = 0; i < sz; i++){printf("%d ", *(p + i));}return 0;
}int main()
{int arr[10] = { 1,2,3,4,5,6,7,8,9,10 };int (* p)[10] = &arr;int i = 0;int sz = sizeof(arr) / sizeof(arr[0]);for (i = 0; i < sz; i++){//printf("%d ", (*p)[i]);printf("%d ", (*p)[i]);//           (*&arr)[i]//              arr[i]}return 0;
}数组指针，会在二维数组中使用void test(int arr[3][5], int r, int c)
{int i = 0;for (i = 0; i < r; i++){int j = 0;for (j = 0; j < c; j++){printf("%d ", arr[i][j]);}printf("\n");}
}void test(int (*p)[5], int r, int c)
{int i = 0;for (i = 0; i < r; i++){int j = 0;for (j = 0; j < c; j++){printf("%d ", *(*(p + i)+j));}printf("\n");}
}int main()
{int arr[3][5] = { {1,2,3,4,5},{2,3,4,5,6},{3,4,5,6,7} };test(arr, 3, 5);return 0;
}int main()
{int arr[10] = { 1,2,3,4,5,6,7,8,9,10 };int i = 0;for (i = 0; i < 10; i++){printf("%d ", arr[i]);}return 0;
}int Add(int a, int b)
{return a + b;
}int* test(char* s)
{return NULL;
}//函数指针变量的写法给数组指针变量的写法非常类似
int main()
{int* (*pt)(char*) = test;int arr[8] = {0};int (*pa)[8] = &arr;//pa是数组指针变量int (*pf)(int, int) = &Add;//pf 就是函数指针变量int x = 10;int y = 20;int z = Add(x, y);printf("%d\n", z);printf("%p\n", &Add);printf("%p\n", Add);//&函数名和函数名都表示函数的地址return 0;
}int Add(int a, int b)
{return a + b;
}int main()
{int (* pf1)(int, int) = &Add;int (* pf2)(int, int) = Add;int r1 = (*pf1)(3, 7);int r2 = (*pf2)(3, 7);int r3 = Add(3, 7);printf("%d\n", r1);printf("%d\n", r2);printf("%d\n", r3);return 0;
}函数声明
函数调用
void (*p)();
0x0012ff40《C陷阱和缺陷》
int main()
{(* ( void (*)() ) 0 )();//函数调用// 1. 将0强制类型转换成void (*)()类型的函数指针// 2. 调用0地址处放的这个函数return 0;
}函数声明
声明的函数的名字叫：signal
signal函数有2个参数，第一个参数的类型是int
第二个参数的类型是void(*)(int)的函数指针类型，该指针可以指向一个函数，指向的函数参数是int，返回类型是void
signal函数的返回类型是void(*)(int)的函数指针，该指针可以指向一个函数，指向的函数参数是int，返回类型是voidvoid (* signal(int, void(*)(int) ) )(int);
void (*)(int) signal(int, void(*)(int));//errtypedef unsigned int uint;int main()
{unsigned int num1;uint num2;return 0;
}typedef 对指针类型重命名typedef int* pint;int main()
{int* p1 = NULL;pint p2 = NULL;return 0;
}typedef int(*parr_t)[5] ;
//parr_t 等价于 int(*)[5]int main()
{int arr[5] = {0};int (* p)[5] = &arr;//p是数组指针变量，p是变量的名字//int (*)[5] -- 数组指针类型parr_t p2 = &arr;return 0;
}void test(char* s)
{}//对函数指针类型重命名产生新的类型pf_t
typedef void (*pf_t)(char*) ;int main()
{void (*pf)(char*) = test;//void (*)(char*)pf_t pf2 = test;return 0;
}void (*signal(int, void(*)(int)))(int);//简化后的代码
typedef void(*pf_t)(int);
pf_t signal2(int, pf_t);typedef int* ptr_t;#define PTR_T int*int main()
{//ptr_t p1;//p1是整型指针//PTR_T p2;//p2是整型指针ptr_t p1, p2;//p1, p2是整型指针PTR_T p3, p4;//p3是指针，p4是整型//int *p3, p4;return 0;
}