A magic square is a square matrix in which the sum of every row, every column, and both main diagonals is the same number (called the magic constant). This C program reads a square matrix and checks whether it is a magic square. Example: 8 1 6 3 5 7 4 9 2 Every row, …
Replacing a substring means finding every occurrence of one piece of text inside a string and swapping it for another — for example, turning “the cat sat on the mat” into “the cog sog on the mog” by replacing “at” with “og”. C has no built-in function for this (unlike Python’s str.replace()), so it’s a …
Chapter 2: Types, Operators, and Expressions covers C’s type system and operators in depth. The exercises focus on bitwise manipulation — rotating bits, setting and clearing fields, counting set bits — and type-conversion edge cases. Exercise 2-9 (x &= (x-1) deletes the rightmost 1-bit) is a classic bit-manipulation trick worth memorising. These are worked solutions …
Finding the position of a substring means locating the index where one string first appears inside another — for example, “world” starts at index 6 in “hello world”. This is one of the most common string operations in C, used for parsing text, validating input, and implementing search features. The standard library already provides strstr() …
Chapter 1: A Tutorial Introduction is where K&R C begins — and it moves faster than most C books. By exercise 1-8 you are counting characters by category; by 1-13 you are drawing histograms; by 1-22 you are folding long lines. The chapter uses only a tiny subset of C deliberately: loops, if/else, basic functions, …
There are two standard ways to check file size in C: the portable fseek()/ftell() method that works with any FILE pointer, and the POSIX stat() method that reads file metadata without opening the file. This page covers both, with complete working programs, a comparison table, and when to use each. Method 1 — fseek() and …