C Interview Questions for MNCs

Predict the output or error(s) for the following:

1. void main()

{

int const * p=5;

printf("%d",++(*p));

}

Answer:

Compiler error: Cannot modify a constant value.

Explanation:

p is a pointer to a "constant integer". But we tried to change the

value of the "constant integer".

2. main()

{

char s[ ]="man";

int i;

for(i=0;s[ i ];i++)

printf("\n%c%c%c%c",s[ i ],*(s+i),*(i+s),i[s]);

}

Answer:

mmmm

aaaa

nnnn

Explanation:

s[i], *(i+s), *(s+i), i[s] are all different ways of expressing the

same idea. Generally array name is the base address for that array. Here s is

the base address. i is the index number/displacement from the base address. So,

indirecting it with * is same as s[i]. i[s] may be surprising. But in the case of C

it is same as s[i].

3. main()

{

float me = 1.1;

double you = 1.1;

if(me==you)

printf("I love U");

else

printf("I hate U");

}

Answer:

I hate U

Explanation:

For floating point numbers (float, double, long double) the values

cannot be predicted exactly. Depending on the number of bytes, the precession

with of the value represented varies. Float takes 4 bytes and long double takes

10 bytes. So float stores 0.9 with less precision than long double.

Rule of Thumb:

Never compare or at-least be cautious when using floating point

numbers with relational operators (== , >, <, <=, >=,!= ) .