Difference between revisions of "CIS 3020 Part 6"
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| Line 72: | Line 72: | ||
Exiting count2(4) | Exiting count2(4) | ||
</pre> | </pre> | ||
| + | || | ||
| + | * count1 has no deferred operations -- when the recursive call is completed, no further calculations must be done. | ||
| + | * This is tail recursive and an interative process. | ||
| + | * Some languages will optimize its implementation eliminating the recursion. | ||
| + | * count2 has a deferred operation -- the print operation is deferred until '''after''' the recursive call. | ||
| + | * This is a recursive process and cannot be optimized. | ||
| + | * Note that both are implemented using recursion. | ||
|} | |} | ||
Revision as of 12:01, 13 April 2007
Ordering of Statements in Methods
Consider the following two methods:
public void count1(int x) {
if (X <= 0) {
System.out.println(x);
} else {
System.out.println(x);
count1(x-1);
}
}
|
public void count2(int x) {
if (X <= 0) {
System.out.println(x);
} else {
count2(x-1);
System.out.println(x);
}
}
|
- Do they calculate the same values?
- Do they do the calculations in the same way?
- Do they print the same results?
Execution
Entering count1(4) 4 Entering count1(3) 3 Entering count1(2) 2 Entering count1(1) 1 Entering count1(0) 0 Exiting count1(0) Exiting count1(1) Exiting count1(2) Exiting count1(3) Exiting count1(4) |
Entering count2(4) Entering count2(3) Entering count2(2) Entering count2(1) Entering count2(0) 0 Exiting count2(0) 1 Exiting count2(1) 2 Exiting count2(2) 3 Exiting count2(3) 4 Exiting count2(4) |
|
