Important Points about strlen()

The following points should be kept in mind while using strlen():

• strlen() does not count the NULL character ‘\0’.
• The time complexity of strlen() is O(n), where n is the number of characters in the string.
• Its return type is size_t ( which is generally unsigned int ).

The strlen() function in C calculates the length of a given string. The strlen() function is defined in string.h header file. It doesn’t count the null character ‘\0’.