Follow the instructions for starting C++ and viewing the Advanced29.cpp file, whic...

Follow the instructions for starting C++ and viewing the Advanced29.cpp file, which is contained in either the Cpp7\Chap13\Advanced29 Project folder or the Cpp7\Chap13 folder. (Depending on your C++ development tool, you may need to open the project/solution file first.) If necessary, delete the two forward slashes that appear before the system("pause"); statement and/or the #include directive, and then save the program. The program assigns the letters of the alphabet to a string variable named letters. It also prompts the user to enter a letter. Complete the program by entering instructions to perform the tasks listed in Figure 13-51. Save and then run the program. Test the program appropriately.