Program Structure

Most c++ programs have a structure like the program in this file

When we run the program, we get output that looks like:

The square of 27 is 729
The CUBE of 27 is 19683

There is a main routine.
There are a number of other functions
What is a function in algebra? (f(x) = x^2+3x+2)
Things between { and } go togeather. They mark a body of code.
In this case, we have the body for the main routine, the body for the functions square and cube.
When the computer runs the code, it runs the first instruction in the main routine, then the next instruction, then the next instruction, then ...
- Line 1: cout << "The square of 27 is ";
  - Prints The square of 27 is to the screen
- Line 2: cout << square(27) ;
  - calls the routine square with argument 27
    - int square (int n) {
    - Says that the routine will return an integer.
    - Also says that the routine wants an integer as input.
    - variable n has the value 27
    - It calculates n*n (27*27) = 729
    - It returns this value to the main routine.
  - The main routine prints this value out.
- Line 3 cout << endl;
  - Prints out an end-of-line marker.

Must contain a main routine.
Should return a value
- In UNIX 0 usually means success
- In UNIX < 0 means failure.