CSE 303, Spring 2005, Assignment 5C (I/O)Due: Tuesday 17 May, 9:00AMLast up dated: May 16Summary: You will write a C file that implements an interface for returning successive words that are readfrom a file. You will also write unit tests for the code you write. The sample solution, not including unittests, is about 55 lines.You may not use any global variables; any state that your file needs to maintain in order to return the nextword must be pointed to by the “info pointer” described below. For actually reading input from the file, usethe getline function as in previous homeworks.1. Include the following type definitions:typedef struct InputInfo * input_info_t;struct InputInfo {...};The fields of struct InputInfo should include:• A FILE* for the file from which input is read.• A char* for the buffer whose address is passed to getline.• A int describing the length of the buffer passed to getline. (This field’s address is also passedto getline.)• A char* that points to the “current position” in the buffer.2. Implement the function input_info_t initialize_input(char * filename). It should open the filenamed filename for reading (printing an error message and exiting the program if opening it fails).It should return a pointer to a new heap-allocated struct InputInfo. It should read the first lineof the file and initialize the fields of the struct InputInfo appropriately. In particular, the “currentposition” should be the beginning of the buffer holding the first line of the file because no words havebeen read yet. You may assume the file has at least one character in it.3. Implement the function char * next_word(input_info_t info). The result is a new heap-allocated,’\0’ terminated string containing (a copy of) the next word in the input file stored in a field of *info.Words contain only English lette rs (either case) and the hyphen (’-’) character. Any other characteris not part of a word. Words are separated by one or more other characters. If there are no more wordsin the file, return NULL.Notes:• The standard C library has a function isalpha.• Some executions of next_word will need to call getline, but others will just advance the “currentposition”.• It is up to the caller to free the space for the string when it is no longer needed.4. Implement the function void complete_input(input_info_t info) to close the file and deallocatethe space consumed by *info and the buffer returned from getline. Be sure you close the file,do not create space leaks, and do not follow dangling pointers. It is up to the caller not to use aninput_info_t after passing it to complete_input.5. Write unit tests for the functions above. Include comments indicating what different tests accomplishand a main function that runs your tests.1Extra Credit: Change your implementation such that hyphenated words can span lines. That is, if thelast character on a line before the ’\n’ character is ’-’, then the word continues onto the next line. Notethat a word could span any number of lines, not just 1 or 2.Assessment: Your solutions should be:• Correct C programs that compile without warnings using gcc -Wall.• In good style, including indentation and line breaks• Of reasonable sizeTurn-in Instructions:• Follow the link on the course website and follow the instructions there.• Problems 1–4 should have solutions in word_io.h and word_io.c; your unit tests should bein word_io_test.c.• We should be able to compile your program via gcc word_io.c word_io_test.c, assuming word_io.his in the same directory.• You can also turn in one test input
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