string evenIndex(string s){ //return a string formed by the characters at even index (0,2,4,...) of the string s }

If s and t are strings, then index function (s, t) in C++ or a similar language would be the int that is the value of the function at the ordered pair (s, t). Translate this function into a standard mathematical function specification.

The question should be done in C++, please give explanation and running result.  1. Let’s write a function that compares 2 strings and returns true if they were identical, false otherwise. The signature of this function should be: bool word_diff(std::string word1, std::string word2);  For example: std::string str1 = "Hello World";std::string str2 = "hEllO World";std::string str3 = "World";std::string str4 = "Hello World";bool result = word_diff(str1, str2); // Falsebool result = word_diff(str1, str3); // Falsebool result = word_diff(str1, str4); // True   2. Now let’s follow a classical approach to compare the content of 2 files. We should open each file, read their content word by word and compare them until a first mismatch occurs.Let’s implement a function called classical_file_diff that takes 2 arguments each of which is a file name and returns a boolean indicating whether the 2 files are identical or not. The signature of this function should be: bool…

Write code for the C++ function given below: bool isPermutation(string str1, string str2){ //returns true if str1 is a permutation of str2, else returns false