指针用于存储变量的地址。因此，当我们定义一个指针到指针时，第一个指针用于存储第二个指针的地址。因此它被称为双指针。
算法
Begin
Declare v of the integer datatype.
Initialize v = 76.
Declare a pointer p1 of the integer datatype.
Declare another double pointer p2 of the integer datatype.
Initialize p1 as the pointer to variable v.
Initialize p2 as the pointer to variable p1.
Print “Value of v”.
Print the value of variable v.
Print “Value of v using single pointer”.
Print the value of pointer p1.
Print “Value of v using double pointer”.
Print the value of double pointer p2.
End.
一个理解双指针的简单程序：
示例
int main() {
int v = 76;
int *p1;
int **p2;
p1 = &v;
p2 = &p1;
printf("Value of v = %d\n", v);
printf("Value of v using single pointer = %d\n", *p1 );
printf("Value of v using double pointer = %d\n", **p2);
return 0;
}
输出
Value of v = 76 Value of v using single pointer = 76 Value of v using double pointer = 76
