Swap the case of every letter in a string and print the result

Convert a camelCase identifier into underscore-separated lowercase

Encode a string using the ROT13 substitution cipher

char *rev_str(char *str)

Mirror lowercase letters to their opposite, leave uppercase unchanged

Replace only the last occurrence of a character in a string

Display characters common to two strings, ordered by their position in the second string

Print each argument with the first letter of every word uppercased and the rest lowercased

Uppercase the last alphabetic character of each word and lowercase the rest

Convert a snake_case identifier into lowerCamelCase format

Advance each letter by one position in the alphabet, wrapping z to a

Merge two strings printing each unique character once, ordered by the second string then the first