Pointer ใช้เก็บ address ของ variables ดังนั้น pointer to pointer ตัวแรกเก็บ address ของตัวที่สอง เรียกว่า double pointers
Algorithm
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.
โปรแกรมง่ายเพื่อเข้าใจ double pointer:
ตัวอย่าง
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; }ผลลัพธ์
Value of v = 76 Value of v using single pointer = 76 Value of v using double pointer = 76
