Find the Position of a Substring in C

Posted on March 20, 2012July 2, 2026 by Sandeepa Nadahalli

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() …

C Program to accept a string and a substring and check if the substring is present in the given string

Posted on October 3, 2011June 29, 2026 by Sandeepa Nadahalli

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 …