Both String#includes() and String#indexOf() are case sensitive . Neither function supports regular expressions. To do case insensitive search, you can use regular expressions and the String#match() function, or you can convert both the string and substring to lower case using the String#toLowerCase() function.16 May 2019
Read moreAre strings in C case-sensitive?
It is case-insensitive . The behavior is NOT undefined (it is well-defined) if either string is a null ptr. Regular strncmp() has undefined behavior if either string is a null ptr (see: https://en.cppreference.com/w/cpp/string/byte/strncmp).
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