Designing I/O

1. Immediately before cin is used to input data from the keyboard, the program should always prompt the user to enter the proper data. For example,
   
   cout << "Enter the number of candy bars in a package\n";
   cout << "and the weight in ounces of one candy bar.\n";
   cout << "Then press return\n";
   cin >> number_of_bars;
   cin >> one_weight;
   
   
2. Should always end the program with endl or \n.
   
   
3. \n is an example of an escape sequence. It is a single non-printable character. Another useful escape sequence is \t, which represents a horizontal tab (usually 8 spaces). In general the backslash \ tells the compiler to interpret the next character differently.
   
   Other escape sequences are:
   \a alert
   \\ a single backslash
   \" a double quote
   
   
4. Formatting numbers with a decimal point for output
   
   • The output stream cout has member functions that allows one to control the output format of numbers with decimal points (floats and doubles)
     
   • Example:
     Using the code:
     cout.setf(ios::fixed); // always uses fixed point rather than scientific notation
     cout.setf(ios::showpoint); // always shows a decimal point
     cout.precision(5); // shows exactly 5 decimal places with rounding;
     //the output of a number such as 3.14159625358979 will appear as 3.14160