GATE | GATE IT 2006 | Question 20

Which of the following statement(s) is TRUE?

1. A hash function takes a message of arbitrary length and generates a fixed length code.
2. A hash function takes a message of fixed length and generates a code of variable length.
3. A hash function may give the same hash value for distinct messages.

 
(A) I only
(B) II and III only
(C) I and III only
(D) II only


Answer: (C)

Explanation:  

Hash function is defined as any function that can be used to map data of arbitrary size of data to a fixed size data.. The values returned by a hash function are called hash values, hash codes, digests, or simply hashes  :  Statement 1 is correct
Yes, it is possible that a Hash Function maps a value to a same location in the memory that’s why collision occurs and we have different technique to handle  this problem : Statement 3 is correct.
eg : we have hash function, h(x) = x mod 3

Acc to Statement 1, no matter what the value of ‘x’ is h(x) results in a fixed mapping location.
Acc. to Statement 3, h(x) can result in same mapping mapping location for different value of ‘x’ e.g. if x = 4 or x = 7 , h(x) = 1 in both the cases, although collision occurs.

This solution is contributed by Mohit Gupta.

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