C语言中的指针初阶详解

#include <stdio.h>
int main()
{
 int a = 10;
 return 0;
}

scanf("%d",&a);

#include <stido.h>
int main()
{
    int a = 10;
    int *pa = &a;//这样就把取出的a的地址存放到指针pa中了
    return 0;
}

    int a = 10;
    int *pa = &a;

short i = 10;
short *pi = &i;

char j = 10;
char * pj = &j;

#include <stido.h>
int main()
{
    int a = 10;
    int *pa = &a;
    *pa = 20;
    return 0;
}

int*pa
int *pa
int* pa
int * pa

#include <stdio.h>
int main()
{
 printf("%zd\n", sizeof(char *));
 printf("%zd\n", sizeof(short *));
 printf("%zd\n", sizeof(int *));
 printf("%zd\n", sizeof(double *));
 return 0;
}

#include <stdio.h>
int main()
{
 int n = 0x12345678;
 int *pi = &n; 
 *pi = 0; 
 printf("%d",n):
 return 0;
}

#include <stdio.h>
int main()
{
 int n = 0x12345678;
 char *pi =(char*) &n; //强制转化，不然是不可以用char类型的指针来接受int类型的变量的
 *pi = 0; 
 printf("%d",n);
 return 0;
}

#include <stdio.h>
int main()
{
	int arr[10] = { 1,2,3,4,5,6,7,8,9,10 };
	int* p = &arr[0];
	int i = 0;
	int sz = sizeof(arr) / sizeof(arr[0]);
	for (i = 0; i < sz; i++)
	{
		printf("%d ", *(p + i));//p+i 这⾥就是指针+整数
	}
	return 0;
}

#include <stdio.h>
int my_strlen(char* s)
{
	char* p = s;
	while (*p != '\0')// \0 之前的元素为字符串中的元素
		p++;
	return p - s;
}
int main()
{
	printf("%d\n", my_strlen("abc"));
	return 0;
}

#include <stdio.h>
int main()
{
	int arr[10] = { 1,2,3,4,5,6,7,8,9,10 };
	int* p = &arr[0];
	int i = 0;
	int sz = sizeof(arr) / sizeof(arr[0]);
	while (p < arr + sz) //指针的⼤⼩⽐较
	{
		printf("%d ", *p);
		p++;
	}
	return 0;
}

#include <stdio.h>
int main()
{
	int* p;//局部变量指针未初始化，默认为随机值
	*p = 20;
	return 0;
}

#include <stdio.h>
int main()
{
	int arr[10] = { 0 };
	int* p = &arr[0];
	int i = 0;
	for (i = 0; i <= 11; i++)
	{
		//当指针指向的范围超出数组arr的范围时，p就是野指针
		*(p++) = i;
	}
	return 0;
}

#include <stdio.h>
int* test()
{
	int n = 100;
	return &n;
}
int main()
{
	int* p = test();
	printf("%d\n", *p);
	return 0;
}

#include <stdio.h>
int main()
{
	int m = 0;
	m = 20;//m是可以修改的
	const int n = 0;
	n = 20;//n是不能被修改的
	return 0;
}

int * p;//没有const修饰
const int * p;//const 放在*的左边做修饰
int const * p;//const 放在*的左边做修饰
int * const p;//const 放在*的右边做修饰