Code in C

2. Create & Test a function that changes a passed string to opposite case (i.e., upper case characters are changed to lowercase and vice versa). This function will take a pointer to a string as input and will return the pointer to the resulting string back. Non-alphabets should remain unchanged. Note: Your string may be long (spans over multiple lines). Do not use static allocation. Your function should have the following interface: Input (function arguments): Pointer to a string (i.e., character array / pointer) to convert Output (function return value): Pointer to the start of the converted string buffer. Note: Do not update the interface without a valid reason or explanation