This function compare n character in two strings to find out whether they are same or different.
The two string are compared character by character until there is a mismatch or end of one of the strings is reached, whichever occurs first.
If the two strings are identical, strncmp() return zero.
If they are not, it returns the numeric difference between the ASCII values of the first non-matching pair of characters.
(Compare ASCII values of string's characters)
if both string equal = 0
if first string > second string = +ve
if first string < second string = -ve
Note: strncmp() is case sensitive.