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1. [20pts] Assume the declarations and function definitions below. Fill in the table. Note: "error" is a possiblity! Note: each question is independent, i.e. no side effects of one expression should be taken to carry over to the next.

   
   string s = "happy";
   string t = "sad";
   string foo() {
     return "good";
   }
   char bar(string str) {
     int i = str.length()-1;
     return str[i];
   }
   bool testcap(char c) {
     return ('A' <= c && c <= 'Z');
   }
   

   
   
   

   expression	type (or error!)	value (or error!)
   s[1]
   t[2] - 'a' + 'A'
   foo() + 2.5
   s[0] = t[0]
   bar(foo())
   foo()[3]
   bar(s[0])
   testcap(s)
   testcap(s[0])
   testcap(s[0] + t[0])
2. [80Pts] We will write a program that performs Ceaser shift cipher. You can revisit the SY110 notes on shift cipher, if you want. Here are sample runs:

   ~/$ ./shift
   Enter a shift value: 3
   Enter a plaintext message (lower-case letters only): abc
   def
   
   ~/$ ./shift
   Enter a shift value: 3
   Enter a plaintext message (lower-case letters only): capitalize
   fdslwdolch
   
   ~/$ ./shift
   Enter a shift value: 20
   Enter a plaintext message (lower-case letters only): capitalize
   wujcnufcty
   

   Assume that the plaintext always contain only the lower-case letters. I already wrote some code for you. Complete the function definitions that so the result code may work as above.

   
   #include <iostream>
   #include <string>
   using namespace std;
   
   //============================================================
   // prototypes
   // c: input character,  n: shift amount
   char shift(char c, int n);
   
   // w: input string,  n: shift amount
   string shift(string w, int n);
   
   //============================================================
   // main function: I already wrote the easy part for you. 
   int main() {
     // get a shift value from the user
     int n;
     cout << "Enter a shift value: ";
     cin >> n;
   
     // get a plaintext message from the user
     string s;
     cout << "Enter a plaintext message (lower-case letters only): ";
     cin >> s;
   
     // shift cipher!!
     cout << shift(s,n) << endl;
   }
   
   //============================================================
   // function definitions
   char shift(char c, int n) {
     // to do: fill in the code!!
   }
   
   string shift(string w, int n) {
     // to do: fill in the code!!
   }
   

   Turn In: A screen capture of a terminal window showing the program running on the sample inputs from above, and a codeprint printout of the source code for the three programs.