Need some help with these 3 parts including some comment lines to help me understand the program better. I've checked other works but they don't seem to work properly. The program is in C++.

If input is 1: call int calculate(string exp) function. This function will return the computation of a string expression (exp). For example:

calculate(54321+222) will return 54543

calculate(120*20) will return 2400

calculate(235/3) will return 78

calculate(356-32) will return 324

If input is 2: call void getFileContent(string filename, vector& words). This function will read a text file and store each word into a vector of string. You have the flexibility to determine the input parameter(s) and output type of the function.

If input is 3: call stopWordRemoval(vector& words,). This function will remove all the stop words from words, where stopwords= {a, an, the, i, we, they};