Unit 3 Guided Practice 3: Passing Variables By Address

You may pass variables to functions either by address or by value.  If you pass a variable by address, then both functions will see the changed value of the variable (if the value changes).  If you pass a variable by value, you're really passing a copy of the variable, and the calling function will not see the changed value of the variable (if the called function changes its value).

Of note in this example:

We pass a variable by prepending the variable name with an ampersand (&).

The receiving function (in this case, do_fun()), prepends the variable name with an asterisk (*). This tells the receiving function that it's receiving the variable's address, not a copy of the variable.  

Notice that the new value of the variable amt is visible in the do_fun() function and in main().

Here is the code: