C语言 指针：C语言中的*p和&p
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pointer: *p and &p in C programming language
提问by mercedes
Could you please tell me the difference between *p and &p in C programming language? cause I really have problem with this and I don't know whether *p or &p is ok!!!!
你能告诉我 C 语言中 *p 和 &p 的区别吗？因为我真的有这个问题，我不知道 *p 或 &p 是否可以！！！！
回答by Avnish Mehta
A pointer is a variable whose value is the address of another variable, i.e., direct address of the memory location. Like any variable or constant, you must declare a pointer before you can use it to store any variable address. The general form of a pointer variable declaration is:
指针是一个变量，其值是另一个变量的地址，即内存位置的直接地址。与任何变量或常量一样，您必须先声明一个指针，然后才能使用它来存储任何变量地址。指针变量声明的一般形式是：
type *var-name;
eg:
例如：
int *ip; /* pointer to an integer */
double *dp; /* pointer to a double */
float *fp; /* pointer to a float */
char *ch /* pointer to a character */
Look at this program :
看看这个程序：
#include <stdio.h>
int main ()
{
int var = 20; /* actual variable declaration */
int *ip; /* pointer variable declaration */
ip = &var; /* store address of var in pointer variable*/
printf("Address of var variable: %x\n", &var );
/* address stored in pointer variable */
printf("Address stored in ip variable: %x\n", ip );
/* access the value using the pointer */
printf("Value of *ip variable: %d\n", *ip );
return 0;
}
回答by Gopi
Just take
就拿
int a =10;
int *p = &a;
ais a variable which holds value 10. The address in which this value is stored is given by &a.
a是一个保存值 10 的变量。存储该值的地址由 给出&a。
Now we have a pointer p, basically pointer points to some memory location and in this case it is pointing to memory location &a.
现在我们有一个指针p，基本上是指向某个内存位置的指针，在这种情况下它指向内存位置&a。
*pgives you 10
*p给你 10
This is called dereferencing a pointer.
这称为取消引用指针。
p = &a /* Gives address of variable a */
Now let's consider
现在让我们考虑
&p
&p
Pointer is a also a data-type and the location in which p is stored is given by &p
指针也是一种数据类型，存储 p 的位置由下式给出 &p
