Answer any two questions. Each question carries a total of 50 marks.

Note: In each of the functions you write, if a string needs to be modified or created then it may be stored in any string which has been passed to the function.

1

Write the function pattern_match(char *pattern, char *string) where string is an arbitrary character string and pattern is a character string composed of the characters X, 9, and the special symbols - (hyphen), . (dot), / (slash) and the space character.

pattern-match returns a 1 if wherever there is an X in pattern there is a alphabetic character in string, wherever there is a 9 in pattern there is a digit in string, and wherever there is a special symbol in pattern , the same symbol occurs in string. pattern-match returns a 0 if string does not match the pattern and -1 if pattern contains characters other than those specified above.

Examples:

pattern-match("X999 XXX", "G567 FOL") = 1.

pattern-match("99-X.99", "11/g.87") = 0.

pattern-match("99*L", "99*L") = -1.

2

(a). Write the function tail(char *string1), which returns a pointer to the string string1 without the leading character. E.g., tail("hello") returns a pointer to the string "ello".

(b). Write the function strncmp(char *string1, char *string2, int n), which returns 1 if the first n characters in string1 exactly match the first n characters in string2, and 0 otherwise.

(c). Write the function substr(char *string, int m, int n) which returns a pointer to a string composed of the substring from the mth to the n th characters of string. Include error checking. What should substr() return if an error has been detected?

3

(a). Write the function membern(char character, char *string2, int n) which returns 1 if character occurs exactly n times in string2 , and 0 otherwise.

(b). Define a data structure that can be used to store a linked list of characters.

(c). Write a C statement which requests space to store a new instance of the data structure defined in 3(b).

(d). Assuming that the last item in the list points to NULL, write a function which traverses the linked list in sequence, printing out each character stored in the list.