Exercise 7-5. Rewrite the postfix calculator of Chapter 4 to use scanf and/or sscanf to do the input and number conversion. The original Chapter 4 calculator used a custom getop() that read characters one at a time with getch/ungetch to recognise numbers vs operators. With scanf we replace that with a simpler approach: read one …
Exercise 7-4. Write a private version of scanf analogous to the private printf described in this section. Like minprintf, minscanf parses a format string and uses va_list to accept a variable number of pointer arguments. It reads from stdin and dispatches to the appropriate conversion — using scanf itself with a constructed sub-format string, so …
Exercise 7-3. Revise minprintf to handle more of the other facilities of printf. K&R’s minprintf (Section 7.3) handles only %d and %s. The cleanest way to extend it: as we parse the format string, collect the complete format specifier (flags, width, precision, length modifier, conversion character) into a local buffer, then call printf with that …
Exercise 7-2. Write a program that will print arbitrary input in a sensible way. As a minimum it should print non-graphic characters in octal or hex (according to local custom), and fold long lines. The rules: Printable characters (isprint) pass through as-is \n resets the column counter; \t and other non-printable characters are shown as …
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 …