strcspn() in C

The strcspn() is a part of the C standard library, it is defined in the <string.h> header file in C. The strcsspn function is used to find the number of characters in the given string before the 1st occurrence of a character from the defined set of characters or string.

Syntax of strcspn()

where,

• str1 : The Target string in which search has to be made.
• str2 : Argument string containing characters to match in target string.

Return Value

This function returns the number of characters in the first string before the 1st occurrence
of character present in second string.

Examples of strcspn()

These C programs demonstrate the use of strcspn() for various scenarios.

Using strcspn() to find characters before matching Character

str1: geeksforgeeks
str2: kfc
The number of characters in str1 before 
first matched character from str2: 3

Using Strcspn() for a simple word game in C

Rules : In this game, 2 players play and one player initially generated a string and is asked to produce a string which has as many unmatched characters. After 1 round, player producing string with maximum unmatched characters wins.

Match Drawn!! 
Score: 2

Program for string validation using strcspn()

In this program the strcspn() is used to check if the string is valid, a valid string must not contain any special character like "!@#$%&*".