83: Mainline

The following sample program illustrates how you can accumulate several variable values. When using the program, you would separate each typed integer by a space, tab, or carriage return.

#include  
main ( ) { 
  int average, size_one, size_two, size_three; 
  printf ("Please type three trade sizes.\n"); 
  scanf ("%i", &size_one); 
  scanf ("%i", &size_two); 
  scanf ("%i", &size_three); 
  average = (size_one + size_two + size_three) / 3; 
  printf ("The average of the trade sizes is %i.\n", average); 
} 

When you execute the program, presuming you have named it average_size, you could witness the following:

average_size                      <-- You type this 
Please type three trade sizes.    <-- The program types this 
600 100 200                       <-- You type this 
The average of the trade sizes is 300.  <-- The program types this 

When you use the average_size program, you can use spaces, tabs, or carriage returns to separate the integers and to mark the end of the final integer.

Note that, if you are using the Unix operating system, the characters that you type accumulate temporarily in an input buffer before delivery to your program. Delivery occurs only when you type a carriage return. Accordingly, the average_size program lies inert until you not only type three integers, but also supply a carriage return following the third one.

Spaces separate integers 
   |   | 
   v   v  
600 100 200 <-- Carriage return marks the end of a line of input and 
                delivers the accumulated characters to your program