if (value >= 2) {
return 1
} else if (value >= 1) {
return 0.9;
} else if (value >= 0.8) {
return 0.7
} else if (value >= 0.5) {
return 0.5;
} else {
return 0;
}
How to solve this if-else ladder. If i use switch cyclometric complexity increases and also also values feels like true.
In some cases the solution is breakaway code. Not everyone likes it - I do like it.
It just means you handle situations "from the top" and end situations with a return
pseudocode in any language...
(Everything should be in a function anyway...)
HandleTemperature(float t)
{
if (t > 90)
{
RunEmergencyCooling();
return;
}
if (round.t == 63)
{
DealWithgMagicValue();
return;
}
if (round.t > 40)
{
Debug.("normal temps! no worries!);
return;
}
// if you get to here, temp is very lopw
RunEmergencyHeating();
}
(In many languages there's a "finally" or "always do" concept, which can work well w/. breakaway dcode.)
Your example ...
Step 1, put in in a function as it should be anyway, Step 2 use "breakaway chunks".
float HandleValue(float v)
{
if (2.0 <= v) {
return 1
}
if (0.7 < v && v < 2.0) {
return 0.9;
}
if (0.13 <= v && v <= 0.7) {
return 17.6;
}
log didn't find a bracket in HandleValue
return default value
}
Every bracket is totally explicit. You can easily build testing code from there, too.
Those annoying long blocks before errors ...
Breakaway is particularly clean-looking in error cases...
Something()
{
if comms.text != 17.2
{
.. 100s of lines of code here ..
.. they are all indented ..
}
else
{
an error!
}
}
Some (but not all) believe this is better:
Something()
{
if comms.text == 17.2
{
an error!
return; .. note the "return" in breakaway code
}
.. 100s of lines of code here ..
.. no need for indentation ..
}
"Breakaway code" may work for you in some cases; in any event you can be aware of the approach.
Related
This is the code in question:
void DeckTug::StickCallback(unsigned long long evtID, DWORD value)
{
long int val = value;
if (evtID == stickXInputID || evtID == stickAxisXInputID)
stickXpct = (((double)val)) / 325.94;
else if (evtID == stickYInputID || evtID == stickAxisYInputID) {
stickYpct = (((double)val)) / 325.94;
if(isAuto)
if ((stickYpct < 0.0)) {
acPullingTug = true;
tugTBoffset = tugReversed ? towbarAttachAft * (-1.0) : towbarAttachForward;
}
else {
acPullingTug = false;
tugTBoffset = tugReversed ? towbarAttachAft * (-1.0) : towbarAttachForward;
}
}
}
When I compile a debug build, this runs perfectly. When I compile a release build, it does not work. When I attach the visual studio debugger to the release version, I can break on the first if statement and on the closing brace of the function, but I cannot hit a break point anywhere else, and neither stickXpct or stickYpct are ever being assigned anything, although in the debugger I can see that "value" has a valid value, and "evtID" DOES equal one of inputIDs.
In conclusion, it looks to me like, in the release version of the code only, both the first "if" statement and the first "else if" statement only evaluate to false, even when one of them should evaluate to true. Does anyone know what is going on here? because I don't.
Thanks so much,
Farley
Edit: changed answer in response to comments
Try adding volatility
void DeckTug::StickCallback(unsigned long long evtID, DWORD value)
{
long int val = value;
volatile unsigned long long _evtID = evtID;
if (_evtID == stickXInputID || _evtID == stickAxisXInputID)
stickXpct = (((double)val)) / 325.94;
else if (_evtID == stickYInputID || _evtID == stickAxisYInputID) {
stickYpct = (((double)val)) / 325.94;
if(isAuto)
if ((stickYpct < 0.0)) {
acPullingTug = true;
tugTBoffset = tugReversed ? towbarAttachAft * (-1.0) : towbarAttachForward;
}
else {
acPullingTug = false;
tugTBoffset = tugReversed ? towbarAttachAft * (-1.0) : towbarAttachForward;
}
}
}
That should prevent the compiler from optimizing those branches until you can track down why it wants to optimize those branches away.
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i'm a beginner at C++ and i tried to make a script for a Trinity Core World of Warcraft private server but it seems that some of the codes ran successfully and the others are escaped for unknown reason..
here's the code
#include "ScriptPCH.h"
#include "DisableMgr.h"
class LearnSpellsOnLevelUp : public PlayerScript
{
public:
LearnSpellsOnLevelUp()
: PlayerScript("LearnSpellsOnLevelUp"){};
void OnLevelChanged(Player* player, uint8 oldLevel)
{
if (player->getClass() == 3 && player->getLevel() >= 12) // ran
{
if (player->HasSpell(23356)) // ran
return; // ran
else // ran
player->LearnSpell(23356, false); // ran
player->GetSession()->SendAreaTriggerMessage("|cff00FF00You Learnt new Spell [Taming Lesson]!|r"); // ran
}
if (player->getClass() == 9) // Warlock // ran
{
if (player->getLevel() >= 2) // ran
{
if (player->HasSpell(44163)) // ran
return;
else
player->LearnSpell(44163, false); // ran
player->GetSession()->SendAreaTriggerMessage("|cff00FF00You Learnt new Spell [Summon Imp]!|r"); // ran
}
else if (player->getLevel() >= 10)
{
if (player->HasSpell(25112))
return;
else
player->LearnSpell(25112, false);
player->GetSession()->SendAreaTriggerMessage("|cff00FF00You Learnt new Spell [Summon Voidwalker]!|r");
}
else if (player->getLevel() >= 20)
{
if (player->HasSpell(712))
return;
else
player->LearnSpell(712, false);
player->GetSession()->SendAreaTriggerMessage("|cff00FF00You Learnt new Spell [Summon Succubus]!|r");
}
else if (player->getLevel() >= 30)
{
if (player->HasSpell(691))
return;
else
player->LearnSpell(691, false);
player->GetSession()->SendAreaTriggerMessage("|cff00FF00You Learnt new Spell [Summon Felhunter]!|r");
}
else
return;
}
}
};
void AddSC_LearnSpellsOnLevelUp()
{
new LearnSpellsOnLevelUp();
}
i wrote next to the codes that ran successfully // ran
Pay close attention to the order of your getLevel conditions.
if (player->getLevel() >= 2)
{
}
// Here, it's certain that the level is < 2, since it wasn't >= 2.
// Thus, none of these following tests will be true.
else if (player->getLevel() >= 10)
{
}
else if (player->getLevel() >= 20)
{
}
else if (player->getLevel() >= 30)
{
}
else
return;
You should test the levels starting with the greatest one and work your way donwnward.
if (player->getLevel() >= 30)
{
}
// The level is less than 30. Is it greater than 20?
else if (player->getLevel() >= 20)
{
}
// The level is less than 20. Is it greater than 10?
else if (player->getLevel() >= 10)
{
}
// The level is less than 10. Is it greater than 2?
else if (player->getLevel() >= 2)
{
}
else
return;
Looks like there is simply a logic bug. Let's look at this statement:
if (player->getLevel() >= 2) // ran - ok so far
And now a lot of this:
else if (player->getLevel() >= 10) - and others (comparing with 20, 30)
Now suppose your 'player' has 15 level - looks like the intent was to run the second if block (e.g. where you compare with >= 10)
But there is a problem: if the level is 15 then everytime only the first if-block is executed (because obviously 15 >= 2).
Solution: compare to range, like this:
if ((player->getLevel() >= 2) && (player->getLevel() < 10))
...
else if ((player->getLevel() >= 10) && (player->getLevel() < 20))
...
And so on.
Under my button class, I have this function that checks if the mouse is within the bounds of the button:
bool Button::isMouseOver(int mousePosX, int mousePosY) {
if (button.getPosition().x < mousePosX &&
button.getPosition().x + button.getSize().x > mousePosX &&
button.getPosition().y < mousePosY &&
button.getPosition().y + button.getSize().y > mousePosY) {
return true;
}
return false;
}
And then under my main cpp file I have this logic used to activate the function:
int mousePosX = sf::Mouse::getPosition().x;
int mousePosY = sf::Mouse::getPosition().y;
switch (Event.type) {
case sf::Event::Closed:
window.close();
case sf::Event::MouseButtonPressed:
if (btnPlay.isMouseOver(mousePosX, mousePosY)) {
std::cout << "True\n";
}
}
but for some reason, nothing happens. And I know that this can work, because I have the same exact code in one of my other games and it works fine.
Slightly off topic, you comment
And I know that this can work, because I have the same exact code in
one of my other games and it works fine.
triggered me to think You might want to consider generalizing this and making something like
bool IsInside(windowPos wp, windowSize ws, someOtherPos sop) {
if (wp.x < sop.X &&
wp.x + ws.x > sop.X &&
wp.y < sop.Y &&
wp.y + ws.y > sop.Y) {
return true;
}
return false;
}
bool Button::isMouseOver(Vector2i mousePos) {
return IsInside(getPosition(), getSize(), mousePos) ;
}
Note types in IsInside are not exact and might actually be the same ( Vector2i ).
This also makes testing easier for correctness and removes a source of errors with copied code.
I'm sure you've been there. You want to say "if flib do this, if flob do that, if flab do diet, etc" where any number of them can be true, then at the end you want an "if you didn't do ANY of them".
For example (the examples below are in Swift, as I've been playing with it, but I think the situation is the same in most languages):
let thing = 101
var isInteresting = false
if (thing % 3 == 0) {
println("\"\(thing)\" is a multiple of three.")
isInteresting = true
}
if (thing > 100) {
println("\"\(thing)\" is greater than one hundred.")
isInteresting = true
}
if (thing > 1000) {
println("\"\(thing)\" is greater than one thousand.")
isInteresting = true
}
if !isInteresting {
println("\"\(thing)\" is boring.")
}
I find keeping track of a boolean to tell me whether I did anything or not kinda ungainly.
The only other way I came up with was this:
let thing = 101
let isAMultipleOfThree = (thing % 3 == 0)
let isGreaterThan100 = (thing > 100)
let isGreaterThan1000 = (thing > 1000)
if isAMultipleOfThree {
println("\"\(thing)\" is a multiple of three.")
}
if isGreaterThan100 {
println("\"\(thing)\" is greater than one hundred.")
}
if isGreaterThan1000 {
println("\"\(thing)\" is greater than one thousand.")
}
if !(isAMultipleOfThree || isGreaterThan100 || isGreaterThan1000 ) {
println("\"\(thing)\" is boring.")
}
but if anything that's worse (if you add a new clause you need to remember to add it in three places.
So my question is, is there a neat, succinct way of doing this?
I'm dreaming of an imaginary switch-like statement:
switchif { //Would have fallthrough where every case condition is checked
case thing % 3 == 0:
println("\"\(thing)\" is a multiple of three.")
case thing >100 :
println("\"\(thing)\" is greater than one hundred.")
case thing > 1000:
println("\"\(thing)\" is greater than one thousand.")
none: //Unlike 'default' this would only occur if none of the above did
println("\"\(thing)\" is boring.")
}
It's a good question that does not have a perfect answer. However, here's one other idea in addition to those you suggest: Encapsulate the testing machinery in a procedure to allow the calling code at least to be a bit more streamlined.
Specifically, for your example, the calling code can be this:
if (! doInterestingStuff(101)) {
println("\"\(thing)\" is boring.");
}
If testing is encapsulated into a procedure:
public boolean doInterestingStuff(int thing) {
var isInteresting = false
if (thing % 3 == 0) {
println("\"\(thing)\" is a multiple of three.")
isInteresting = true
}
if (thing > 100) {
println("\"\(thing)\" is greater than one hundred.")
isInteresting = true
}
if (thing > 1000) {
println("\"\(thing)\" is greater than one thousand.")
isInteresting = true
}
return isInteresting
}
I'm not sure how you'd do this in Swift, but since you didn't give a language tag I'll answer in C++.
The key to this is that && is short circuiting, and the second part won't be evaluated when the first part is false. It's the same idea as your boolean flag, but it's a little more automated.
struct Tracker
{
Tracker() : any(false) { }
bool operator()() { any = true; return true; }
bool any;
};
int thing = 101;
Tracker tracker;
if (thing % 3 == 0 && tracker()) {
printf("\"%d\" is a multiple of three.\n", thing);
}
if (thing > 100 && tracker()) {
printf("\"%d\" is greater than one hundred.\n", thing);
}
if (thing > 1000 && tracker()) {
printf("\"%d\" is greater than one thousand.\n", thing);
}
if (!tracker.any) {
printf("\"%d\" is boring.\n", thing);
}
See it in action: http://ideone.com/6MQYY2
kjhughes' answer inspired me a little:
Perhaps one could write a global function that accepts an indeterminate number of key-value pairs (or even just two element arrays), where the key is a comparison and the value is the statement to run if it's true. Then return false if none of them were run, otherwise true.
Update:
Tried it, it's horrible!
//Function:
func ifNone(ifNoneFunc:()->Void, tests: Bool...)
{
var oneTestPassed = false
for test in tests
{
oneTestPassed |= test
}
if(!oneTestPassed)
{
ifNoneFunc()
}
}
//Example:
let thisThing = 7
ifNone(
{
println("\(thisThing) is boring")
},
{
if(thisThing % 10 == 0)
{
println("\"\(thisThing)\" is a multiple of 10")
return true
}
else
{
return false
}
}(),
{
if(thisThing % 3 == 0)
{
println("\"\(thisThing)\" is a multiple of 3")
return true
}
else
{
return false
}
}(),
{
if(thisThing > 1_000_000)
{
println("\"\(thisThing)\" is over a million!!")
return true
}
else
{
return false
}
}()
)
I am writing a program in which I use an if statement to check some condition; if true I increment a counter. The problem is that as soon as the statement is true the variable either gets incremented endlessly or by random number.
I have been trying to use some clause to break out of this statement if condition meet but with no luck
my code:
if(res_vect_angle >=60 && res_vect_angle <=100 && left_mag_b >100)
{
//line(drawing, *iter_s, *(iter_s -1), Scalar( 255, 255, 255 ), 2,8 );
left_hook_count++;
cout<<"Left Hook:..........................!!! "<<left_hook_count<<endl;
if(left_hook_count++ == true)
{
break;
}
}
The whole chunk of code associated with the issue:
float M1, M2;
float A1, A2;
double left_mag_a, left_mag_b;
double res_vect_angle;
int i = 0;
for(vector<Point>::iterator iter_lh = Leftarm.begin(); iter_lh != Leftarm.end(); ++iter_lh)
{
if(iter_lh->y <=240 && iter_lh->y >=60 && iter_lh->x >=340 && iter_lh->x <=680)
{
left_detect.push_back(*iter_lh);
if(i % 4 == 0)
{
if(left_detect.size()>4)
{
for(vector<Point>::iterator iter_s = left_detect.begin()+3; iter_s != left_detect.end(); ++iter_s, i++)
{
//Resultant Magnetude
M1 = pow((double) iter_s->x + (iter_s -2)->x,2);
M2 = pow((double) iter_s->y + (iter_s -2)->y,2);
left_mag_a = (M1 + M2);
left_mag_b = sqrt(left_mag_a);
//Resultant Angle
A1 = abs(iter_s->x - (iter_s -2)->x);
A2 = abs(iter_s->y - (iter_s -2)->y);
res_vect_angle = abs(atan2(A1,A2) * 180 /PI);
//cout<<"LEFT HOOK ANGLE IS: "<<res_vect_angle<<endl;
if(res_vect_angle >=60 && res_vect_angle <=100 && left_mag_b >100)
{
//line(drawing, *iter_s, *(iter_s -1), Scalar( 255, 255, 255 ), 2,8 );
left_hook_count++;
cout<<"Left Hook:..........................!!! "<<left_hook_count<<endl;
if(left_hook_count++ == true)
{
break;
}
}
}
}
}
}
}
Hope this helps guys ps. left_hook_count++; is a int variable declared on top of my main().
The best solution is probably to invert the test, and make all the rest of the outer if conditional:
if (whatever) {
// do some stuff
if (left_hook_count != true) { // or whatever the test should really be
// do some more stuff
}
}
You could get the program flow you want using goto with a label after the outer if, but you don't want to.
On the other hand, it sounds like perhaps this is in a loop, and you don't want to enter the if block at all if the counter has been incremented? In that case you want:
if (left_hook_count == 0 && whatever) {
// do some stuff
}
you could provide more details so that we can figure out whats happening.
You might not have initialized it?
and checking again
if(left_hook_count++ == true)
it will increment it again unneccessariy and for for first count (0 : it wont happen)
i guess you 're using some recursive function. so check for Break condition (all test cases too).
Don't compare left_hook_count++ to true. In this context, true is equal to 1, and once left_hook_count exceeds 1, this test will fail and the code will never hit the break.
And you don't break out of an if statement. You break out of a loop; a break in an if statement inside the loop is one way of doing this.
You can just negate the condition, instead of trying to break out of the if:
if(...) {
if(!left_hook_count++) {
// Do what you need to do
}
}
my new answer:
:mylabel if (some_condition)
{
//code
if (some_condition) {break mylabel;}
//code
}
my old answer: Replace the if statement with a while statement containing a unconditional break at the end.
(old answer was before I learned of attaching labels to statement blocks.)
In your case:
while(res_vect_angle >=60 && res_vect_angle <=100 && left_mag_b >100)
{
//line(drawing, *iter_s, *(iter_s -1), Scalar( 255, 255, 255 ), 2,8 );
left_hook_count++;
cout<<"Left Hook:..........................!!! "<<left_hook_count<<endl;
if(left_hook_count++ == true)
{
break;
}
break; //this unconditional break makes the while loop act as an if statement
}
However if you don't have code after the conditional break what's the point of having it? I'm assuming you've omitted that code? The way you wrote it it would simply break out of the inner for loop.