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';//err
return 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");//1
else
printf("str1 and str2 are not same\n");//2
if (str3 == str4)
printf("str3 and str4 are same\n");//3
else
printf("str3 and str4 are not same\n");//4
return 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int
return 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void
void (* signal(int, void(*)(int) ) )(int);
void (*)(int) signal(int, void(*)(int));//err
typedef 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;
}
原文地址：https://blog.csdn.net/do_yo/article/details/142887898
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