Write the function findFirst(). The function has two parameters: a const char * s1 pointing to the first character in a C-style string, and a const char * s2. Return a pointer to the first appearance of s2 appearing inside s1 and nullptr (0) if s2 does not appear inside s.

** You may not use ANY library functions

or include any headers, except for for size_t. and for testing.

Please explain your steps. Thanks.