Tuesday, August 3, 2010

C Question Set 2-7


  1. main(){

int k=1;


printf("%d==1 is ""%s",k,k==1?"TRUE":"FALSE");


}


Answer:


1==1 is TRUE


Explanation:


When two strings are placed together (or separated by white-space) they are concatenated (this is called as "stringization" operation). So the string is as if it is given as "%d==1 is %s". The conditional operator( ?: ) evaluates to "TRUE".


 


  1. main(){

int y;


scanf("%d",&y); // input given is 2000


if( (y%4==0 && y%100 != 0) || y%100 == 0 )


printf("%d is a leap year");


else


printf("%d is not a leap year");


}


Answer:


2000 is a leap year


Explanation:


An ordinary program to check if leap year or not.


 


  1. #define max 5

#define int arr1[max]


main(){


typedef char arr2[max];


arr1 list={0,1,2,3,4};


arr2 name="name";


printf("%d %s",list[0],name);


}


Answer:


Compiler error (in the line arr1 list = {0,1,2,3,4})


Explanation:


arr2 is declared of type array of size 5 of characters. So it can be used to declare the variable name of the type arr2. But it is not the case of arr1. Hence an error.


Rule of Thumb:


#defines are used for textual replacement whereas typedefs are used for declaring new types.


 


  1. int i=10;

main()    {


extern int i; {


int i=20;{


const volatile unsigned i=30;


printf("%d",i);


}


printf("%d",i);


}


printf("%d",i);


}


Answer:


30,20,10


Explanation:


'{' introduces new block and thus new scope. In the innermost block i is declared as, const volatile unsigned which is a valid declaration. i is assumed of type int. So printf prints 30. In the next block, i has value 20 and so printf prints 20. In the outermost block, i is declared as extern, so no storage space is allocated for it. After compilation is over the linker resolves it to global variable i (since it is the only variable visible there). So it prints i's value as 10.


 


  1. main(){

int *j;{


int i=10;


j=&i;


}


printf("%d",*j);


}


Answer:


10


Explanation:


The variable i is a block level variable and the visibility is inside that block only. But the lifetime of i is lifetime of the function so it lives upto the exit of main function. Since the i is still allocated space, *j prints the value stored in i since j points i.


 


  1. main(){

int i=-1;


-i;


printf("i = %d, -i = %d \n",i,-i);


}


Answer:


i = -1, -i = 1


Explanation:


-i is executed and this execution doesn't affect the value of i. In printf first you just print the value of i. After that the value of the expression -i = -(-1) is printed.


 


  1. main() {

const int i=4;


float j;


j = ++i;


printf("%d %f", i,++j);


}


Answer:


Compiler error


Explanation:


i is a constant. you cannot change the value of constant


 


  1. main(){

int a[2][2][2] = { {10,2,3,4}, {5,6,7,8} };


int *p,*q;


p=&a[2][2][2];


*q=***a;


printf("%d..%d",*p,*q);


}


Answer:


garbagevalue..1


Explanation:


p=&a[2][2][2] you declare only two 2D arrays. but you are trying to access the third 2D(which you are not declared) it will print garbage values. *q=***a starting address of a is assigned integer pointer. now q is pointing to starting address of a.if you print *q meAnswer:it will print first element of 3D array.


 


  1. main() {

register i=5;


char j[]= "hello";


printf("%s %d",j,i);


}


Answer:


hello 5


Explanation:


if you declare i as register compiler will treat it as ordinary integer and it will take integer value. i value may be stored either in register or in memory.


 


  1. main(){

int i=5,j=6,z;


printf("%d",i+++j);


}


Answer:


11


Explanation:


The expression i+++j is treated as (i++ + j).

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