Interview Preparation topic : Pointers in C - Revision history

Proj user10: Fix the table format in Q.5

2018-05-22T01:51:46Z

Fix the table format in Q.5

2016-12-18T03:37:00Z

2016-12-18T03:14:58Z

2016-12-15T22:01:06Z

2016-12-15T21:58:18Z

2016-12-15T21:54:52Z

2016-12-11T07:41:49Z

2016-12-11T07:41:10Z

2016-12-11T07:35:53Z

2016-12-11T07:34:48Z

@@ Line 69: / Line 69: @@
 <br>
 ->
-) *ptr = 20 Statement is Invalid in Pointer to              1)  *ptr = 20 is Absolutely Valid in Constant Pointers i.e Assigning Value is Perfectly legal
+               Pointer to Constant                                            Constant Pointer
-          Constant i.e Assigning Value is Illegal
+) *ptr = 20 Statement is Invalid in Pointer to              1) *ptr = 20 is Absolutely Valid in Constant Pointers i.e Assigning Value is
-)  ptr ++  Statement  is Valid in Pointer to Constant       2)  ptr ++  Statement  is invalid in Constant Pointers
+         Constant i.e Assigning Value is Illegal                      Perfectly legal
-)  Declaration : const int *ptr ;                           3) int *const ptr2;
+) ptr ++  Statement  is Valid in Pointer to Constant        2) ptr ++  Statement  is invalid in Constant Pointers
 ) What will be the size of pointer?<br>

@@ Line 64: / Line 64: @@
 ) What is the difference between *ptr++ and ++*ptr?<br>
--> ptr++ means Increments the Pointer not Value Pointed by It<br>
+-> ptr++ means Increments the Pointer not Value Pointed by It, ++*ptr means Increments the Value being Pointed to by ptr
 ) What is the difference between  pointer to constant and constant pointer?<br>

@@ Line 30: / Line 30: @@
     int main ()
+    {
-    int  temp= 100;                                     /* Stores the value 20 in variable temp */
+    int  temp= 100;                                     /* Stores the value 100 in variable temp */
     int  *ptr;                                          /* Declares a pointer variable of type int */
     ptr = &temp;                                         /*store address of temp in pointer variable, so now the address of temp will be in ptr */

@@ Line 67: / Line 67: @@
     ++*ptr means Increments the Value being Pointed to by ptr
-) What is the difference between constant to pointer and pointer to constant?<br>
+) What is the difference between  pointer to constant and constant pointer?<br>
+<br>
-->    No	Pointer to Constant	                                  Constant Pointers
+->
-	 *ptr = 20 Statement is Invalid in Pointer to              1)  *ptr = 20 is Absolutely Valid in Constant Pointers i.e Assigning Value is Perfectly legal
+) *ptr = 20 Statement is Invalid in Pointer to              1)  *ptr = 20 is Absolutely Valid in Constant Pointers i.e Assigning Value is Perfectly legal
            Constant i.e Assigning Value is Illegal
-	  ptr ++  Statement  is Valid in Pointer to Constant       2)  ptr ++  Statement  is invalid in Constant Pointers
+)  ptr ++  Statement  is Valid in Pointer to Constant       2)  ptr ++  Statement  is invalid in Constant Pointers
-  Declaration : const int *ptr ;                           3) int *const ptr2;
+)  Declaration : const int *ptr ;                           3) int *const ptr2;
 ) What will be the size of pointer?<br>

@@ Line 68: / Line 68: @@
 ) What is the difference between constant to pointer and pointer to constant?<br>
 ->    No	Pointer to Constant	                                  Constant Pointers
 	 *ptr = 20 Statement is Invalid in Pointer to              1)  *ptr = 20 is Absolutely Valid in Constant Pointers i.e Assigning Value is Perfectly legal
            Constant i.e Assigning Value is Illegal
 	  ptr ++  Statement  is Valid in Pointer to Constant       2)  ptr ++  Statement  is invalid in Constant Pointers
-   Declaration : const int *ptr ;
+   Declaration : const int *ptr ;                           3) int *const ptr2;
 ) What will be the size of pointer?<br>

@@ Line 32: / Line 32: @@
     int  temp= 100;                                     /* Stores the value 20 in variable temp */
     int  *ptr;                                          /* Declares a pointer variable of type int */
-    ip = &temp;                                         /*store address of temp in pointer variable, so now the address of temp will be in ptr */
+    ptr = &temp;                                         /*store address of temp in pointer variable, so now the address of temp will be in ptr */
     printf("Address of temp variable: %x\n", &temp);    /* print the address of variable temp */
     printf("Address stored in ptr variable: %x\n",ptr ); /* prints the address stored in variable ptr */

@@ Line 77: / Line 77: @@
 -> Size of Pointer Variable does not depends upon data type. Pointer variable only stores the address of the variable and Address of variable is of integer type. So Size of Pointers variables of any type is 2 byte or 4 bytes.
-) What do you mean by function to a pointer?
+) What do you mean by function to a pointer?<br>
 -> Consider the following code:

@@ Line 5: / Line 5: @@
 Lets Look at the following example:
-#include <stdio.h>
+   #include <stdio.h>
-int main ()
+   int main ()
-−
+   {
     int  temp;
     int temp1;
@@ Line 13: / Line 13: @@
     printf("Address of temp1 variable: %x\n", &temp1 );
     return 0;
-−
+   }
 When the following code is compiled and executed:<br>
@@ Line 27: / Line 27: @@
 Consider the following example:<br>
-#include <stdio.h>
+   #include <stdio.h>
-int main () {
+   int main ()
     int  temp= 100;                                     /* Stores the value 20 in variable temp */
     int  *ptr;                                          /* Declares a pointer variable of type int */
@@ Line 36: / Line 37: @@
     printf("Value of *ptr variable: %d\n", *ptr );       /* prints the value stored at address ptr, this is also known as dereferencing of a pointer */
     return 0;
-−
+   }
 When we compile and execute the following code:<br>

@@ Line 93: / Line 93: @@
 ) Parenthesis () indicates that it is a function pointer.
 ) Since there are no parameters the parenthesis are empty.
-) We now have assigned the sayHello function to the function pointer, this is similar to int* x=&z; where we assign the address of z to an int pointer.
+) We now have assigned the sayHello function to the function pointer, this is similar to int* x=&z; where we assign the address of z to an int pointer.<br>
                      line 7. 1) Here we dereference the pointer,by  by using the value-at-address (*) operator.
 ) Again we use the parenthesis() around the pointer to indicate dereferencing of function pointer

@@ Line 79: / Line 79: @@
 -> Consider the following code:
-      #include <stdio.h>;      //1
+      #include <stdio.h>;      //Line 1
-      void sayHello();         //2
+      void sayHello();         //Line 2
-      void sayHello() {        //3
+      void sayHello() {        //Line 3
-      printf("hello world");}  //4
+      printf("hello world");}  //Line 4