Exercise 7-1. Write a program that converts upper case to lower or lower case to upper, depending on the name it is invoked with, as found in argv[0]. Unix convention: a single binary is installed under two names via symlinks (tolower and toupper). argv[0] holds the name used to invoke the program. Checking whether “lower” …
Exercise 6-6. Implement a simple version of the #define processor (i.e., no arguments) suitable for use with C programs, based on the routines of this section. You may also find getch and ungetch useful. The processor reads C source line by line. When it sees #define NAME replacement it calls install from the hash table …
Exercise 6-5. Write a function undef that will remove a name and definition from the table maintained by lookup and install. K&R Section 6.6 presents a hash table with separate chaining: an array of HASHSIZE buckets, each being the head of a linked list of struct nlist nodes. install adds a name/definition pair; lookup finds …
Exercise 6-4. Write a program that prints the distinct words in its input sorted into decreasing order of frequency of occurrence. Precede each word by its count. Count words using K&R’s binary tree (Section 6.5), then collect all nodes into an array and sort by count descending using qsort. The key insight: the tree is …
Exercise 6-3. Write a cross-referencer that prints a list of all words in a document, and for each word, a list of the line numbers on which it occurs. Remove noise words like “the”, “and”, and so on from the list. The data structure is a binary tree where each node holds the word and …
Exercise 6-2. Write a program that reads a C program and prints in alphabetical order each group of variable names that are identical in the first 6 characters, but different somewhere thereafter. Don’t count words within strings and comments. Make 6 a parameter. The strategy: Use the improved getword from Exercise 6-1 to read identifiers, …