I have an if else statements that has 2 values that need to be evaluated whether they're null or not, then based on that, it chooses the right statement. The code below:
int? x;
int? y;
if(x == null and y == null) { do this part; }
else if (x != null and y == null) {do this second part; }
else if (x == null and y != null) {do this third part; }
else { do this last part; }
I am trying to find if there is a more efficient way to implement this. There is the option of a case statement, but I still want to know if there is a better way.
I'd use a nested if, so each variable is only evaluated once, instead of multiple times as suggested in the OP snippet.
if (x == null) {
if (y == null) {
// Both are null
} else {
// Only x is null
}
} else {
if (y == null) {
// Only y is null
} else {
// Neither are null
}
}
Related
In my C# code I'm having the following code:
if (A == null)
{
errors.Add(nameof(A), "A does not exist.");
return Task.CompletedTask;
}
else if (B == null)
{
errors.Add(nameof(B), "B does not exist.");
return Task.CompletedTask;
}
where types A and B are treated identically. I am therefore experimenting if these conditions can be merged to obtain more concise code!
Would it be possible to write something like
if (A == null || B == null)
{
errors.Add(nameof(A/B), "A/B does not exist."); // When A == null, use A. When B == null, use B.
return Task.CompletedTask;
}
where we can retrieve information about which type is null? In other words, can we find out which of the conditions in the if-statement was satisfied?
Thanks in advance!
You could use ternary operator.
if (A == null || B == null)
{
errors.Add(nameof(A == null ? A : B), $"{A == null ? "A" : "B"} does not exist."); // When A == null, use A. When B == null, use B.
return Task.CompletedTask;
}
I have run into a very weird issue recently. I deployed a new version of a program and am receiving this error when the IComparer.Compare() method gets called internally:
Unable to sort because the IComparer.Compare0 method returns inconsistent
results. Either a value does not compare equal to itself, or one value repeatedly
compared to another value yields different results. x:",x's type: 'String',
IComparer.".
The odd thing is that I cannot reproduce this issue on my computer. It doesn't happen for me in Visual Studio 2013 (debug or release versions) and it doesn't happen when I install the application either. To make things weirder, it doesn't even happen on every computer in production, only about 30% of them.
My application targets .NET Framework 4 and the platform target is x86.
There is only one instance of an IComparer object in my code, here it is:
public int Compare(string stringOne, string stringTwo)
{
if (stringOne == stringTwo) { return 0; }
else if (stringOne == null) { return stringTwo == null ? 0 : -1; }
else if (stringTwo == null) { return stringOne == null ? 0 : 1; }
else if (stringOne.StartsWith("_") && !stringTwo.StartsWith("_"))
{
return -1;
}
else if (!stringOne.StartsWith("_") && stringTwo.StartsWith("_"))
{
return 1;
}
else if ((stringOne.StartsWith("l") || stringOne.StartsWith("L")) &&
(!stringTwo.StartsWith("l") || !stringTwo.StartsWith("L")))
{
return -1;
}
else if ((!stringOne.StartsWith("l") || !stringOne.StartsWith("L")) &&
(stringTwo.StartsWith("l") || stringTwo.StartsWith("L")))
{
return 1;
}
else
{
if (stringTwo == null) { return 1; }
else { return stringOne.CompareTo(stringTwo) == 1 ? -1 : 1; }
}
}
Has anyone else had this issue and found a solution to it? Does my comparer look it covers all cases? I am totally lost about this issue and have no idea what to try next. Any help will be greatly appreciated.
This
else if ((stringOne.StartsWith("l") || stringOne.StartsWith("L")) &&
(!stringTwo.StartsWith("l") || !stringTwo.StartsWith("L")))
{
return -1;
}
else if ((!stringOne.StartsWith("l") || !stringOne.StartsWith("L")) &&
(stringTwo.StartsWith("l") || stringTwo.StartsWith("L")))
{
return 1;
}
should be
else if ((stringOne.StartsWith("l") || stringOne.StartsWith("L")) &&
!(stringTwo.StartsWith("l") || stringTwo.StartsWith("L")))
{
return -1;
}
else if (!(stringOne.StartsWith("l") || stringOne.StartsWith("L")) &&
(stringTwo.StartsWith("l") || stringTwo.StartsWith("L")))
{
return 1;
}
As a side note, the way you wrote this comparer function is highly ineffecient.
This is the code giving a stack overflow it only happens about half the time and i have no idea why it's doing it. From what I seen it only happens with the Coms(TopCom, etc) are in a mass of numbers so around 5+ then it stack overflows.
public bool getConnected(int d) {
if (topCom.connection != null) {
if (d != topCom.connection.id) {
if (topCom.connection.id == 0) {
return true;
} else if (topCom.connection.connected == true) {
if (Development.instance.currentDos.buttons[topCom.connection.id].getConnected(id)) {
return true;
}
}
}
}
if (leftCom.connection != null) {
if (d != leftCom.connection.id) {
if (leftCom.connection.id == 0) {
return true;
} else if (leftCom.connection.connected == true) {
if (Development.instance.currentDos.buttons[leftCom.connection.id].getConnected(id)) {
return true;
}
}
}
}
if (rightCom.connection != null) {
if (d != rightCom.connection.id) {
if (rightCom.connection.id == 0) {
return true;
} else if (rightCom.connection.connected == true) {
if (Development.instance.currentDos.buttons[rightCom.connection.id].getConnected(id)) {
return true;
}
}
}
}
if (botCom.connection != null) {
if (d != botCom.connection.id) {
if (botCom.connection.id == 0) {
return true;
} else if (botCom.connection.connected == true) {
if (Development.instance.currentDos.buttons[botCom.connection.id].getConnected(id)) {
return true;
}
}
}
}
return false;
}
This happens in recursive functions where you don't have a base condition for ending the recursion. You basically keep calling the function until you reach stack overflow.. Trace your code through and figure out why it calls itself endlessly.
The fact that people here can't really tell what you're trying to accomplish is a code smell of sorts.
A big part of that is the fact that you have an incredible amount of nesting in your code. Nested conditionals increase the difficulty of debugging code, as you're discovering now. Additionally, you could easily combine some of your conditionals - all of your conditionals in any top-level branch can actually be combined into one statement, as follows:
if ((topCom.connection != null && d != topCom.connection.id && topCom.connection.id == 0) ||
(topCom.connection.connected == true &&
Development.instance.currentDos.buttons[topCom.connection.id].getConnected(id)))
{
return true;
}
return false;
As far as I can imagine, there's no point in having separate conditional branches that perform the same function, e.g. if (a) { return true; } else if (b) { return true; }. Just move the logic from else if into the original if conditional.
However, I'd recommend encapsulating some or all of this logic into a separate function, given that it seems like you're performing the same logic on each of your connections. You could create a function like so:
public bool ConnectionIsValid(connectionObject // replace with the actual type)
{
if (topCom.connection != null && d != topCom.connection.id && topCom.connection.id == 0)
|| (topCom.connection.connected == true
&& Development.instance.currentDos.buttons[topCom.connection.id].getConnected(id))
return true;
return false;
}
So that you could then just call ConnectionIsValid on each of your connections, rather than using 80-some lines on conditionals for each connection.
It also seems doubtful that there's a StackOverflowException occurring in this code. Unless you have a circular reference related to any of the objects referenced in this code (in which case, there's a decent chance you used a setter accessor to assign a value to the same variable:
object A
{
set
{
this.A = value;
}
}
which will always cause a stack overflow, it's likely you've introduced some sort of recursion outside the scope of the included code.
Suppose I have this if statement:
foreach (MyModel m in SomeList)
{
if (m.pID != SomeValue && (m.xID != 0 && SomeFunction(m.xID) == false)
{
return false;
}
}
I only want SomeFunction(m.xID) == false to evaluate if m.xID != 0 so if m.xID == 0 then don't evaluate SomeFunction
For the moment, I have this if statement broken down into 2 statements and I'm looking to see how I can combine these into just one while preserving the logic. This is the original:
foreach (MyModel m in SomeList)
{
if (m.xID != 0 && SomeFunction(m.xID) == false)
{
return false;
}
if (m.pID != SomeValue)
{
return false;
}
}
If that is all your loop is doing then I would be inclined to remove the loop entirely.
Also, instead of comparing something to false, just use the ! operator.
if (SomeList.Any(MyModel m=>m.xID != 0 && !SomeFunction(m.xID) || m.pID != SomeValue))
return false;
you are looking for this || Operator (C# Reference)
if ((m.xID != 0 && SomeFunction(m.xID) == false) || (m.pID != SomeValue))
{
return false;
}
I have a logic like below and i have a counter
if(condition1 == true)
{
// do something
if (counter==1)
{
// break and go to last else statement
}
}
else if (condition2==true)
{
if (counter == 2)
{
// break and go to last else statement
}
// do something
}
else
{
// do this
}
how do i use break in this logic ?
i tried putting goto tag for else but apparently it is not valid . and i want to avoid switch as there is too much logic.
counter will be 2 in second if else loop and if counter = 2 then first if and secong if else should execute if counter=3 then first if second if else third if else should execute ans so on –
Note: Question was changed, this answer is meanwhile incorrect!
You can change the if/else if to include the counter. Then you don't need a break or goto:
if (condition1 && counter != 1)
{
// do something
}
else if (condition2 && counter != 2)
{
// do something
}
else
{
// do this
}
use something like
if (condition1 && ( counter != 1 || counter != 2 || .... counter!= n )
{
// do something
}
else if (condition2 && (counter != 2 || .. || counter!= n )
{
// do something
}
and so on
else
{
// do this
}
Apart from the fact that a break statement doesn't jump outside an if condition, your code could be
refactored in a more simple way (just pretend that the closed brace after the first if it's only a typo)
if(condition1 ==true && counter != 1)
{
do something
}
else if (condition2==true && counter != 2)
{
do something
}
else
{
do this
}
I suspect that your algorithm could be entirely redesigned, but without more context that's impossible to know.
In the meantime, you can refactor your final else clause into a separate method. You don't actually need to use break (which isn't valid in an if statement anyway), with judicious use of else.
private void MyMethod()
{
if(condition1)
{
// do something
if (counter==1)
{
MyOtherMethod();
}
}
else if (condition2)
{
if (counter == 2)
{
MyOtherMethod();
}
else
{
// do something
}
}
else
{
MyOtherMethod()
}
}
private void MyOtherMethod()
{
// Do what was in your final else clause.
}
Prior to your question edits that moved the `do something' in the first if clause to before the counter check, this would have worked too:
Assuming your various "do something" statements were different things:
if (condition1 && counter != 1)
{
// Do something.
}
else if (condition2 && counter != 1)
{
// Do something.
}
else
{
// Do something else.
}
Just put the logic in the last else block in a seperate function which you can call whenever / wherever you want.
Don't. Using a break and continue in such a big loop adds complexity and clutters your logic.
If a loop is getting too big, use one or more well-named function calls within the loop instead.
bool myCondition = false;
if(condition1 ==true)
{
if (counter==1){myCondition = true;}
// do something
}
else if (condition2==true)
{
if (counter==1){myCondition = true;}
// do something
}
// so on
if(myCondition)
{
// do this
}