To sort a string alphabetically in C, apply bubble sort to the character array: compare adjacent characters and swap them when the left character is greater than the right. After all passes, the characters are in ascending ASCII order — digits first, then uppercase A–Z, then lowercase a–z. For a sort that treats ‘A’ and …
Reversing a string in C means rearranging its characters so the last character becomes the first and vice versa: “Hello” becomes “olleH”. The standard technique is the two-pointer swap — place one pointer at the start and one at the end, swap the characters they point to, then move the pointers toward each other until …
Chapter 7: Input and Output covers the standard I/O library in depth — formatted output with printf, formatted input with scanf, file access with fopen/fclose, line I/O with fgets/fputs, and error handling via stderr. The chapter also introduces variable-argument functions (stdarg.h) through a worked minprintf example. The exercises range from practical utilities (a case-converter, a …
Converting a number to words means printing its English name: 4562 becomes four thousand five hundred sixty two. This is useful in invoice generation, banking applications, and cheque printing. The logic handles a key edge case — the teens (11–19) — where the tens digit 1 does not produce “ten X” but a single combined …
Chapter 6: Structures introduces struct, typedef, and self-referential structures (linked lists, binary trees). The chapter builds a word-frequency counter using a binary tree, then extends it with a hash table. Exercise 6-3 adds a cross-reference listing; 6-6 implements a rudimentary #define processor using a hash table — the most complex exercise in this chapter. These …