Pointer learning

    
    One 、 Defining pointer variables
（1) Type name ：* Pointer variable name
      char  *pa;   // Define a pointer variable that points to a character type
      int   *pb;  // Define a pointer variable that points to an integer
 （2) Take address operator and value operator
      If you need to get the address of a variable , You can use the address operator （&）：
                    char *pa=&a;
                    int    *pb=&b;
    If you need to access the data pointed to by the pointer variable , You can use the value operator （*）：
                    printf（“%c,%d\n”,*pa,*pb）;

#include<stdio.h>
int main()
{
	char a = 'F';
	int f = 123;
	
	char *pa = &a;
	int *pb = &f;
	printf("a=%c\n", *pa);       //  Initial pointer variable 
	printf("f=%d\n", *pb);

	*pa = 'C';
	*pb += 1;

	printf("now,a=%c\n", *pa);     // Change the pointer variable 
	printf("now,f=%d\n", *pb);

	printf("sizeof pa=%d\n", sizeof(pa));   // Print pointer length 
	printf("sizeof pb=%d\n", sizeof(pb));

	printf("the adds a or b is:%p\n",pa);    // Access pointer address 
	printf("the adds a or b is:%p\n", pb);
	return 0;
}

  ** You need to avoid uninitialized pointers

#include <stdio.h>
int main()
{
	int *a;               //  Uninitialized pointer 
	*a = 123;

	return 0;
}