Checking whether one string contains another is one of the most common string operations in C. The standard library provides strstr() in <string.h> — it returns a pointer to the first occurrence of the substring in the main string, or NULL if not found. The position of the match is calculated by subtracting the start …
This C program shows how to mask password input with asterisks (*) — exactly what you see on a login screen, where each character you type is hidden behind a *. The trick is to read the keyboard without echoing the typed character to the screen, print a * in its place, and store the …
Inserting an element into an array means placing a new value at a specific position while shifting existing elements to make room. Because C arrays are fixed in size, you need to allocate enough space upfront and track the current number of elements separately. This guide shows two practical approaches: inserting at a given index …
This program reads N integers into a dynamically allocated array and computes their sum using pointer arithmetic instead of array subscript notation. Understanding the equivalence between *(a + i) and a[i] is fundamental to C — both produce identical machine code. The program also demonstrates malloc() and free() for runtime-sized arrays. The original post used …
A matrix is a 2D array of numbers arranged in rows and columns. Finding the sum of its elements — row by row, column by column, or all at once — is one of the most common matrix operations and a good exercise in nested loops and function design. This post shows two approaches: a …
Selection Sort works by repeatedly finding the minimum element from the unsorted portion of the array and placing it at the beginning. After each pass, the sorted portion grows by one element from the left. It always performs exactly O(n²) comparisons regardless of input order — unlike Bubble or Insertion Sort, there is no early …