Tuesday, May 5, 2009

QUESTION No. 131-140

131) main()

{

char str1[] = {'s','o','m','e'};

char str2[] = {'s','o','m','e','\0'};

while (strcmp(str1,str2))

printf("Strings are not equal\n");

}

Answer:

"Strings are not equal"

"Strings are not equal"

….

Explanation:

If a string constant is initialized explicitly with characters, '\0' is not

appended automatically to the string. Since str1 doesn't have null

termination, it treats whatever the values that are in the following

positions as part of the string until it randomly reaches a '\0'. So

str1 and str2 are not the same, hence the result.


 

132) main()

{

int i = 3;

for (;i++=0;) printf("%d",i);

}

Answer:

Compiler Error: Lvalue required.

Explanation:

As we know that increment operators return rvalues and

hence it cannot appear on the left hand side of an

assignment operation.


 

133) void main()

{

int *mptr, *cptr;

mptr = (int*)malloc(sizeof(int));

printf("%d",*mptr);

int *cptr = (int*)calloc(sizeof(int),1);

printf("%d",*cptr);

}

Answer:

garbage-value 0

Explanation:

The memory space allocated by malloc is uninitialized, whereas

calloc returns the allocated memory space initialized to zeros.


 

134) void main()

{

static int i;

while(i<=10)

(i>2)?i++:i--;

printf("%d", i);

}

Answer:

32767

Explanation:

Since i is static it is initialized to 0. Inside the while loop the

conditional operator evaluates to false, executing i--. This

continues till the integer value rotates to positive value (32767).

The while condition becomes false and hence, comes out of the

while loop, printing the i value.


 

135) main()

{

int i=10,j=20;

j = i, j?(i,j)?i:j:j;

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

}

Answer:

10 10

Explanation:

The Ternary operator ( ? : ) is equivalent for if-then-else

statement. So the question can be written as:

if(i,j)

{

if(i,j)

j = i;

else

j = j;

}

else

j = j;

136) 1. const char *a;

2. char* const a;

3. char const *a;

-Differentiate the above declarations.

Answer:

1. 'const' applies to char * rather than 'a' ( pointer to a constant

char )

*a='F' : illegal

a="Hi" : legal

2. 'const' applies to 'a' rather than to the value of a (constant

pointer to char )

*a='F' : legal

a="Hi" : illegal

3. Same as 1.


 

137) main()

{

int i=5,j=10;

i=i&=j&&10;

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

}

Answer:

1 10

Explanation:

The expression can be written as i=(i&=(j&&10)); The inner

expression (j&&10) evaluates to 1 because j==10. i is 5. i = 5&1 is

1. Hence the result.


 

138) main()

{

int i=4,j=7;

j = j || i++ && printf("YOU CAN");

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

}

Answer:

4 1

Explanation:

The boolean expression needs to be evaluated only till the truth

value of the expression is not known. j is not equal to zero itself

means that the expression's truth value is 1. Because it is followed

by || and true || (anything) => true where (anything) will not be

evaluated. So the remaining expression is not evaluated and so the

value of i remains the same.

Similarly when && operator is involved in an expression, when any

of the operands become false, the whole expression's truth value

becomes false and hence the remaining expression will not be

evaluated.

false && (anything) => false where (anything) will not be

evaluated.


 

139) main()

{

register int a=2;

printf("Address of a = %d",&a);

printf("Value of a = %d",a);

}

Answer:

Compier Error: '&' on register variable

Rule to Remember:

& (address of ) operator cannot be applied on register

variables.


 

140) main()

{

float i=1.5;

switch(i)

{

case 1: printf("1");

case 2: printf("2");

default : printf("0");

}

}

Answer:

Compiler Error: switch expression not integral

Explanation:

Switch statements can be applied only to integral types.

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