老生常谈C语言中指针的使用

//首先我们声明一个变量
int a = 10;	//声明一个指针并指向该变量的地址	
int* b = &a;	printf("%d\n", *b);

//首先我们声明一个数组变量
int c[10] = { 0,1,2,3,4,5,6,7,8,9 };		
printf("c的地址:%p\n", c);	
printf("c[0]的地址:%p\n", &c[0]);

int* d=c
printf("d[9]的值为:%d\n",*(d+9));
//另一种写法printf("d[9]的值为:%d\n",d[9]);

void* p = &a;
printf("void指针的值:%d\n", *(int*)p);
//对比b指针变量
printf("这是b的值:%p\n", b);
printf("这是p的值:%p\n", p);

printf("直接使用数组名获取索引3的元素:%d\n", c[3]);
printf("使用指向c的指针获取索引3的元素:%d\n", d[3]);

int g = 50;
int* h = &g;
int** i = &h;
//输出一下
printf("h的值:%p\n", h);
printf("i的值:%p\n", *i);
//实验证明这是可行的,那我们尝试做一个数组
int j[5] = { 9,8,7,6,5 };
int* k[5] = { &j[0],&j[1],&j[2],&j[3],&j[4] };
int** l = k;
printf("k[1]的值:%p,对应的整数的值:%d\n", k[1], *k[1]);
printf("l获取k1的值:%p,对应的整数的值:%d\n", *(l + 1), **(l + 1));

int* m = (int*)malloc(10 * sizeof(int));
for (int i = 0; i < 10; ++i)
	*(m++) = i;

printf("%d\n", *(m - 2));

for (int i = 0; i < 10; ++i)
	(--m);
free(m);

int* n = (int*)malloc(10 * sizeof(int));
for (int i = 0; i < 10; ++i)
	*(n + i) = i;
printf("%d\n", *(n + 8));
free(n);

char o;

char* q = &o;
scanf("%c", q);
printf("通过指针获取输出的字符:%c\n", *q);

char r[] = { "Hello" };
scanf("%s", r);
printf("字符串的值:%s\n", r);

int u[4][4] = { {1,2,3,4},{2,3,4,5},{3,4,5,6},{4,5,6,7} };
int** v = u;

printf("u[1][2]的值:%d\n", *(v + 6));

int** w = (int**)malloc(4 * sizeof(int)); //分配行内存
for (int i = 0; i < 4; ++i)
	w[i] = (int*)malloc(4 * sizeof(int)); //分配列内存
for (int i = 0; i < 4; ++i)
	for (int j = 0; j < 4; ++j)
		w[i][j] = (j + 1) + i;
printf("w[1][2]的值:%d\n", w[1][2]);
free(w); //记得释放

struct people
{
	char* name;
	int age;
}SPeople;
//方便表示替换掉标识符
typedef struct people People;
People dr;
dr.name = "aaa";
dr.age = 18;
printf("dr的名字是:%s,年龄是:%d\n", wusihao.name, wusihao.age);
People* lp = &wusihao; //注意属性获取的符号"->"
lp->name = "sss";
lp->age = 19;
printf("lp的名字是:%s,年龄是:%d\n", lp->name, lp->age);

People* lps = (People*)malloc(1 * sizeof(People));
lps->name = "xxx";
lps->age = 20;
printf("lps的名字是:%s,年龄是:%d\n", lps->name, lps->age);

int* s = &a;
printf("%p\n", s);
s = NULL;

int* t = (int*)malloc(10 * sizeof(int));
if (t == NULL)
{
	//分配错误
	system("pause");
	return 0;
}
else
{
	//你的代码
	system("pause");
	free(t);
}