Pointer, malloc and realloc 1. Name entered was 6 char, not enough space to put null terminator 2 Array of char.

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Presentation transcript:

pointer, malloc and realloc 1

Name entered was 6 char, not enough space to put null terminator 2 Array of char

3 Pointer to array of char

3.cpp(15) : error C2440: '=' : cannot convert from 'int' to 'int *' 4 Pointer to array name[] vs Pointer to variable age (wrong version)

4.cpp(14) : warning C4313: 'printf' : '%d' in format string conflicts with argument 1 of type 'int *' 5 Pointer to array name[] vs Pointer to variable age (correct version)

6 Access address and value pointed by pointer to array name[] Access address and value pointed by pointer to variable age

7 strlen()

8 nameptr points to an empty offset (with size 5 bytes) allocate new memory using malloc, determine no of offset by strlen name azlan [0][1][2][3][4] nameptr

9 char *strcpy(char *destination, const char *source); The argument order mimics that of an assignment: destination "=" source. The return value is destination strcpy() – copy value from array to offset name azlan [0][1][2][3][4] nameptr azlan

10 Null terminator nameptr azlan [0][1][2][3][4] \0 [5] Use for loop to go to each offset

11 azlan [0][1][2][3][4] nameptr Go to the next offset nameptr++ azlan [0][1][2][3][4] [0][1][2][3] nameptr++ will makes nameptr point to the next offset

12 azlan [0][1][2][3][4] name azlan [0][1][2][3][4] nameptr 12ff58 12ff4c ff5912ff5a12ff5b12ff5c &name = &name[0] = 12ff58 Line 16, create 1 byte x 5 offset Line 17, copy string from name to nameptr Check the address for each array name[] element and nameptr offset

13 azlan [0][1][2][3][4] name 12ff5812ff5912ff5a12ff5b12ff5c &name = &name[0] = 12ff58 azlan [0][1][2][3][4] tempptr 12ff4c [0] listptr 12ff **listptr – pointer to pointer

14 [0] ptr 12ff60 364d68 [0] [0] d68 [0] 3631b [1] 3631b [2] 3631b8 listptr 12ff54 realloc() – continue create a new offset, to point to other address

e8 3631b0 3631ec f0 listptr 12ff14 a [0] ptr l [1] i [2] c [0] 3631b0 h [1] 3631b1 o [2] 3631b2 n [3] 3631b3 g [4] 3631b4 m [0] u [1] t [2] h [3] u [4] [0][1][2] when offset=0 when offset=1 when offset=2 Line 11-create new malloc, line 12-copy value from name[] to ptr, line 18-create new offset, line 15 and 19-offset points to where ptr points