Frequently Asked Questions in Technical Round at MNCs like TCS, WIPRO, INFOSYS,..etc – 7

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

1)

main ( )

{

 static char *s[ ]  = {“black”, “white”, “yellow”, “violet”};

 char **ptr[ ] = {s+3, s+2, s+1, s}, ***p;

 p = ptr;

 **++p;

 printf(“%s”,*--*++p + 3);

}

Answer:

ck

Explanation:

In this problem we have an array of char pointers pointing to start of 4 strings. Then we have ptr which is a pointer to a pointer of type char and a variable p which is a pointer to a pointer to a pointer of type char. p hold the initial value of ptr, i.e. p = s+3. The next statement increment value in p by 1 , thus now value of p =  s+2. In the printf statement the expression is evaluated *++p causes gets value s+1 then the pre decrement is executed and we get s+1 – 1 = s. The indirection operator now gets the value from the array of s and adds 3 to the starting address. The string is printed starting from this position. Thus, the output is ‘ck’.

2)

main()

{

 int  i, n;

 char *x = “girl”;

 n = strlen(x);

 *x = x[n];

 for(i=0; i<n; ++i)

   {

printf(“%s\n”,x);

x++;

   }

 }

Answer:

(blank space)

irl

rl

l

 

Explanation:

Here a string (a pointer to char) is initialized with a value “girl”.  The strlen function returns the length of the string, thus n has a value 4. The next statement assigns value at the nth location (‘\0’) to the first location. Now the string becomes “\0irl” . Now the printf statement prints the string after each iteration it increments it starting position.  Loop starts from 0 to 4. The first time x[0] = ‘\0’ hence it prints nothing and pointer value is incremented. The second time it prints from x[1] i.e “irl” and the third time it prints “rl” and the last time it prints “l” and the loop terminates.