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 6-1. Our version of getword does not properly handle underscores, string constants, comments, or preprocessor control lines. Write a better version. K&R’s getword from Section 6.3 reads the next identifier or non-alphabetic character from input, but has four gaps: Underscores: valid in C identifiers (_var, size_t) but the original checks only isalpha String constants: …
Exercise 5-20. Expand dcl to handle declarations with function argument types, qualifiers like const, and so on. The basic dcl treats () as “function returning” but ignores argument types. This exercise adds: parameter lists inside (), type qualifiers (const, volatile), storage classes (static, extern), and the void type. The approach: when ( is encountered and …