Pointers+(2)

Pointers in C C++ Spring 2000 Arrays

Pointers ,[object Object],C++ Spring 2000 Arrays int foo; int *x; foo = 123; x = &foo; foo x 123 3 ... ... MEMORY 0 1 2 3 4 5 81345 81346 81347 Address

Pointers ,[object Object],[object Object],C++ Spring 2000 Arrays “ the int x points to”

Pointers ,[object Object],&foo means “the address of foo” foo int foo; foo = 123; x = &foo; 123 ... ... MEMORY 0 1 2 3 4 5 Address

Assigning a value to a dereferenced pointer ,[object Object],C++ Spring 2000 Arrays int *x; *x=3; int foo; int *x; x = &foo; *x=3; ERROR!!! x doesn’t point to anything!!! this is fine x points to foo

Pointers to anything ,[object Object],[object Object],[object Object],C++ Spring 2000 Arrays x some int some *int some int y z some double

Pointer arithmetic ,[object Object],[object Object],C++ Spring 2000 Arrays int a[5]; a[0] a[1] a[2] a[3] a[4] int *ptr = a; *ptr *(ptr+2) *(ptr+4)

Operations on Pointers ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],C++ Spring 2000 Arrays

Pointer arithmetic ,[object Object],[object Object],[object Object],C++ Spring 2000 Arrays

Q&A ,[object Object],[object Object],[object Object],[object Object],C++ Spring 2000 Arrays

Pointers and Arrays ,[object Object],[object Object],[object Object],[object Object],[object Object],C++ Spring 2000 Arrays x is “the address of a[2] ”

Printing an array using Pointer ,[object Object],[object Object],[object Object],[object Object],[object Object],C++ Spring 2000 Arrays void print_array(int *a , int len) { for (int i=0;i<len;i++) cout << "[" << i << "] = " << *a++ << endl; } pointer version array version

Q&A ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],C++ Spring 2000 Arrays

Q&A ,[object Object],[object Object],C++ Spring 2000 Arrays

[object Object],C++ Spring 2000 Arrays

Call by Value ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Address (2 bytes) 65514 65515 65516 65517 65518 65519 65520 65521 65522 65523 65524 65525 a 4 b 4 8 main myFunc

Call by Reference ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Data Word Size 1 byte (assume) Address Word Size (2 bytes) 65514 65515 65516 65517 65518 65519 65520 65521 65522 65523 65524 65525 a 4 main myFunc 8 b 65520

Passing pointers as parameters ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],C++ Spring 2000 Arrays

Pointer Parameters ,[object Object],[object Object],[object Object],C++ Spring 2000 Arrays

Q&A ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],C++ Spring 2000 Arrays

Pointers and String ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Pointers and String ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Pointers to Structures ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Pointer as Structure Member ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],NULL a b c a.data = 1; a.next->data = 2; /* b.data =2 */ a.next->next->data = 3; /* c.data = 3 */ c.next = (struct node *) malloc(sizeof(struct node)); ……

Pointers+(2)

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