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Pointer Use
Why do we use pointer instead of variable?
jbode
- Sep 30th, 2010
We *must* use pointers for the following:1. To fake pass-by-reference semantics;2. To track dynamically allocated memory;3. To build self-referential data structures.If we want a function to modify...
Cmkraj
- Sep 15th, 2010
List of pros & cons of pointers over variables1. Fetching speed is faster thru pointers as pointers directly access the memory2. Useful in the concepts of pass by reference. variable value can be chan...
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Finding a number which is a power of 2in a single step
How to find whether the given number is a power of 2 in single step (without using loops)?
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When should a type cast be used?
There are two situations in which to use a type cast. The first use is to change the type of an operand to an arithmetic operation so that the operation will be performed properly. The second case is to cast pointer types to and from void * in order to interface with functions that expect or return void pointers. For example, the following line type casts the return value of the call to malloc()...
kbjarnason
- Jul 2nd, 2010
Very, very, *VERY* rarely. My rule of thumb is, if you see a cast, expect a design error.One classic example of this is the oh-so-popular casting of the return value of malloc. Don't d...
srinivasrao
- Oct 9th, 2007
Type cast should be used in case of if we want to assign a void pointer to a pointer of some data type.eg:void *ptr;int *c;c=(int *)ptr;
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What are the characteristics of arrays in C?
1) An array holds elements that have the same data type 2) Array elements are stored in subsequent memory locations3) Two-dimentional array elements are stored row by row in subsequent memory locations.4) Array name represents the address of the starting element5) Array size should be mentioned in the declaration. Array size must be a constant expression...
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If we pass null pointer in malloc or calloc function, What will be the result?
kbjarnason
- Jul 2nd, 2010
You don't pass null pointers to malloc or calloc. You can pass them to realloc.Perhaps you mean what would happen if you did this:#include <stdlib.h>int main(void){ char *p...
kannan987
- Jun 13th, 2008
Test.h is nothing but in my pgm..simply include all header files..<----test.h--->#include<stdio.h>#include<conio.h>#include<stdlib.h>#include<string.h>
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Difference between Funtion to pointer and pointer to function
rocking.piyush
- Feb 23rd, 2011
That are not same.Function to a pointer means the return value of the function is a pointer Ex:- int *func (int x,int y)Whereas pointer to a function is the declaration of pointer that holds the base address of the function. Ex:-int (*func) (int x,int y)
Ajay Kanse
- Dec 22nd, 2008
Both are same. There is lot of confusion around this but function point and pointer to function are same.
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What is pointer?
Pointer is used to store the address of given variable
Priya
- Aug 3rd, 2006
A pointer is a variable, which contains the address of another variable
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How can you get the number of elements in an array allocated dynamically at runtime? For example -int *p = (int *) malloc(sizeof(int) * n);int numElems = ??????? /* n is not available here */
jbode
- Jul 6th, 2010
If all you have is the pointer p, then there is no (standard) way to determine how many elements were allocated to the chunk it's pointing to. If you have to keep track of how big your dynamic b...
kbjarnason
- Jul 2nd, 2010
The short answer is, you can't.With static arrays, you know the size of both the array and its elements and can simply work it out. With dynamically allocated arrays, the size information is...
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What is the type of the variable b in the following declaration?#define FLOATPTR float*FLOATPTR a,b;a) float b) float pointer c) int d) int pointer
Choose the correct option
Sonali Sadhukhan
- Jun 18th, 2011
It should be int as any pointer is of type int.Though it will point to an element of type float...
Rohit Kumar Sharma
- Oct 11th, 2006
Fine that is correct.many commit mistake here carelessly.
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printf("%d %d", i, j);
}
">Main(){ int i, j; scanf("%d %d"+scanf("%d %d", &i, &j)); printf("%d %d", i, j);}
A) Compile errorB) 0, 0C) Runtime error.D) the first two values entered by the userExplanation: two values entered, 3rd will be null pointer assignment
jbode
- Jun 30th, 2010
The behavior is undefined. There are not enough arguments for the given conversion specifiers in the scanf() calls (7.19.6.2.2). It looks like the intent is for the inner call to scanf() t...
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If the program (myprog) is run from the command line as myprog 1 2 3 , What would be the output? main(int argc, char *argv[]) { int i; for(i=0;i<argc;i++) printf("%s",argv[i]); }
A) 1 2 3B) C:MYPROG.EXE123C) MYPD) None of the above
sunilkanna
- Oct 21st, 2009
The answer is b. because command line argument includes file path as first argument.
prabhjots
- Feb 6th, 2008
The result will bec:mypgm.exe123becoz argv[0] will be the location of ur program(be it c: or d:)
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What are storage class in c
abhimanipal
- Jan 24th, 2010
I do not think volatile is a storage class. Volatile is a instruction given to the compiler not to optimize this variable.
Mahananda R.Biradar
- May 12th, 2006
Actually there are only two storage Classe........its given in K & R
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char *s2 = "world";
char *s3 = strcat(s1, s2);
Please provide me explainations??">What is wrong with the following c prog??char *s1 = "hello";char *s2 = "world";char *s3 = strcat(s1, s2);Please provide me explainations??
dasam
- Mar 31st, 2007
Friends, the return value of strcat is not void, it is char*. please see the below line ..char * strcat(char * s1, const char * s2);Thanks :)
UMESH RAM
- Sep 7th, 2006
HI ARTHUR , i m agree with ur ans.strcat doesn't return any char datatypeand constant string cant change its value.
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What is a null macro? What is the differtents between a null pointer and a null macro? What is near, far and huge pointer? How many bytes are occupied by them? How would you obtain segment and offset addresses from a far address of a memory location?
vivianyang
- May 12th, 2008
A null pointer should not be confused with an uninitialized pointer: a null pointer is guaranteed to compare unequal to any valid pointer, whereas depending on the language and implementation an unini...
dasam
- Mar 31st, 2007
NULL MACRO : #define NULL 0NULL Pointer : int* ptr = NULL; //points to no whereuninitialised pointer : int* ptr; //points to anywhere
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The two declarations are different Can you explain where these declarations are applicable effectivelyconst char *s; char const *s;
ardashev
- Nov 17th, 2007
#include <stdlib.h>int main(){ const char *pr1 = malloc(4); char const *pr2 = malloc(4); char * const pr3 = malloc(4); &nbs...
manik sheeri
- Nov 7th, 2006
i think that the both declarations are the sameconst char *s;char const *s;in both cases the string to which s will point cant be changed.but something likechar * const s;means that the pointer is he...
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In c the return value for main() is optional why in c++ the main() must return value ?
jbode
- Feb 1st, 2011
From the C standard:------------------------------5.1.2.2.1 Program Startup1 The function called at program startup is named main. The implementation declares no prototype for this function.&nbs...
abcdef
- Dec 19th, 2006
In c every function by default returns an integer value. By using void we mean a value zero is return to the environment i.e., operating system.
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Is it possible to declare a dynamic array without using malloc,calloc,and pointer.
jbode
- Feb 1st, 2011
C99 introduced the concept of a Variable Length Array (VLA), where the array size doesn't have to be known until runtime:size_t elements=10;int arr[elements];They act pretty much like regular, sta...
Deepam
- Jan 3rd, 2007
No ,its not possible to have a dynamic array without using calloc,malloc or without ptr.... Why u want to know abt it? but u can achieve a array without specifying size say arr[]; but its not eff...
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Why C does not support nested functions?
17shraddha
- Nov 1st, 2010
C does not support nested function try this code void adds(){?? ? printf("Adds start");???? void subbs()???? {???? printf("subbs start");???? }???? printf("adds end");}void main(){?? adds();?? subs();//Will generate an error prototype required}
uharish38
- Jul 8th, 2009
In C every funciton is independant from other.And there is a clear difference from function definition and function invocation.In C the only way to Invoke a function is to call a function.
C Interview Questions
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