Pointer level 2

C ProgrammingPointers – Level-II

Prepared by Mohammed SikanderTechnical LeadCranes Software International Limited

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char *ptr_name = “SIKANDER”;char str_name[ ] = “SIKANDER”;

• Can we make a pointer point to string literal?

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printf(“ %s \n“ , ptr_name);printf(“ %s \n“ , str_name);

• Can we print the string through pointer.

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printf(“Length of %s = %d\n“ , ptr_name , strlen(ptr_name));

printf(“Length of %s = %d\n“ , str_name , strlen(str_name));

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char *ptr_name = “SIKANDER”;char str_name[ ] = “MUQADDAR”;

printf(“Size of ptr_name = %d\n“ , sizeof(ptr_name));

printf(“Size of str_name = %d\n“ , sizeof(str_name));

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Array of Pointers

Array of PointersWe can have arrays where each element can be a pointer

int *

char **

int *

int *

int *

int *

int *arr_ptr[5];

int

int

int

int

int

int arr[5];

What is size of arr?What is size of arr_ptr?

Array of Pointers

char **

Char *arr_ptr[5];

char *

char *

char *

char *

char *

char

char

char

char

char

Char arr[5];

What is size of arr?What is size of arr_ptr?

int x = 10;int *ptr =

&x;

int arr[5] int *ptr =

arr;

int a = 10;int b = 23;int arr[ ] = {12,34,54};int *ptr[ ] = {&a , &b ,

arr};

Array of Pointers

char *capitalCities[] = { “Bangalore”,“Chennai”, “Guwahati”, “Amravathi”};

Bangalore

Chennai

Guwahati

Amravathi

****

char *

char *

char *

char *

char *str = “VxWorks”;

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Array of Pointers

names++ tries to change the base address of array. We cannot change the base address of array. Str was a pointer, names is an array.


Sorting of Strings stored in Array of Pointers


Passing Array of pointers to function.

Array of Pointers

char **

*Bangalor

eChennai

Guwahati

Amravathi NULL

****

char *

char *

char *

char *

void pointers

Void pointers can hold the address of any type of object.

Dereferencing on void pointers are not allowed.

Incrementing void pointers are not allowed.


Void pointer


Program to demonstrate double free corruption.


Program to solve double free corruption.



Trying to delete memory of stack segment using free.


Memory allocated by calloc is set to zero.


Understanding Realloc How many bytes of memory is leaked


Program to understand realloc.If realloc allocates new block in different location, it copies data from old block to new block


Identify the problem


By making ptr as constant pointer, any modification to ptr can be caught at compile time.


Write the output : DMA
