Got a silly question im struggling with.
Im trying to step through a C# Multidimensional array using nested for loops, but i cant get the result i want and im thinking its just a stupid problem with my code.
string search = txtString.Text;
int iLoop;
int jloop;
int iResult = -1;
for (iLoop = 0; iLoop < sounds.GetLength(0) ; iLoop++)
{
for (jloop = 0; jloop < sounds.GetLength(1) ; jloop++)
{
string result;
result = sounds[iLoop,jloop];
if (result == search)
{
iResult = iloop;
}
}
}
if (iResult == -1)
{
MessageBox.Show("Result not found");
}
else
{
MessageBox.Show("Result found at position " + iResult);
}
}
It searches the array, and returns a positive result if the answer is found, but the result position is always "Result found at position 1".
What have i done wrong?
You are storing only one dimension (iResult). It can always be 1, but second dimension (jresult) can vary.
And just reminder for future projects in different languages. Try no to use if (result == search) for strings. Use Equal or Compare methods.
There are two indices to look up: jloop and iLoop , probably you will get various jloop values in the 2D array
Also check the name on the parameter you use, sometimes you call it iLoop, others iloop.
Be consistent! :)
I guess the answer is always in row 1, you just pring the i value, print also the j value jLoop.
Keep in mind that this code snippet will continue searching even after it has found a match. So in fact what you are finding is the last position of the matched text.
As an aside, perhaps instead of reporting only the matching iLoop, you could report both the matching iLoop and jLoop. Or, you can report a single index as iLoop * sounds.GetLength(0) + jLoop
Related
I've been working on a project where I need on a button press that this line gets executed.
if (listView1.SelectedItems[0].SubItems[3].Text == "0") //Checks to see Value
{
listView1.SelectedItems[0].SubItems[3].Text = "1";// If Value is Greater, Increase and Change ListView
questionNumberLabel.Text = listView1.SelectedItems[0].SubItems[3].Text;// Increase and Change Label
}
Now I have this repeated about 10 times with each value increasing by one. But I know that this is ugly, and dysfunctional. As well as conflates the file size. I've tried a few things. Primarily this method.
if (listView1.SelectedItems[0].SubItems[3].Text == "0")
{
for (var i = 1; i < 100;)
{
if (!Int32.TryParse(listView1.SelectedItems[0].SubItems[3].Text, out i))
{
i = 0;
}
i++;
listView1.SelectedItems[0].SubItems[3].Text = i.ToString();
Console.WriteLine(i);
}
}
But instead of just adding one, it does the 100 instances and ends. The reason this is becoming a pain in the *** is because the
listView1.SelectedItems[0].SubItems[3].Text
is just that - it's a string, not an int. That's why I parsed it and tried to run it like that. But it still isn't having the out come I want.
I've also tried this
string listViewItemToChange = listView1.SelectedItems[0].SubItems[3].Text;
Then parsing the string, to make it prettier. It worked like it did before, but still hasn't given me the outcome I want. Which to reiterate is, I'm wanting the String taken from the list view to be changed into an int, used in the for loop, add 1, then restring it and output it on my listView.
Please help :(
You say you want the text from a listview subitem converted to an int which is then used in a loop
so - first your creating your loop variable, i, then in your loop you're assigning to it potentially 3 different values 2 of which are negated by the, i++. None of it makes sense and you shouldn't be manipulating your loop variable like that (unless understand what you're doing).
if you move statements around a little..
int itemsToCheck = 10; // "Now I have this repeated about 10 times "
for (var item = 0; item < itemsToCheck; item++)
{
int i;
if (!Int32.TryParse(listView1.SelectedItems[item].SubItems[3].Text, out i))
{
i = 0;
}
i++;
listView1.SelectedItems[item].SubItems[3].Text = i.ToString();
Console.WriteLine(i);
}
Something along those lines is what you're looking for. I haven't changed what your code does with i, just added a loop count itemsToCheck and used a different loop variable so your loop variable and parsed value are not one in the same which will likely be buggy.
Maybe this give you an idea. You can start using this syntax from C# 7.0
var s = listView1.SelectedItems[0].SubItems[3].Text;
var isNumeric = int.TryParse(s, out int n);
if(isNumeric is true && n > 0){
questionNumberLabel.Text = s;
}
to shortcut more
var s = listView1.SelectedItems[0].SubItems[3].Text;
if(int.TryParse(s, out int n) && n > 0){
questionNumberLabel.Text = s;
}
I'm not sure how best to phrase this. I have a text file of almost 80,000 words which I have converted across to a string array.
Basically I want a method where I pass it a word and it checks if it's in the word string array. To save it searching 80,000 each time I have indexed the locations where the words beginning with each letter start and end in a two dimensional array. So wordIndex[0,0] = 0 when the 'A' words start and wordIndex[1,0] = 4407 is where they end. Then wordIndex[0,1] = 4408 which is where the words beginning with 'B' start etc.
What I would like to know is how can I present this range to a method to have it search for a value. I know I can give an index and length but is this the only way? Can I say look for x within range y and z?
Look at Trie set. It can help you to store many words using few memory and quick search. Here is good implementation.
Basically you could use a for loop to search just a part of the array:
string word = "apple";
int start = 0;
int end = 4407;
bool found = false;
for (int i = start; i <= end ; i++)
{
if (arrayOfWords[i] == word)
{
found = true;
break;
}
}
But since the description of your index implies that your array is already sorted a better way might be to go with Array.BinarySearch<T>.
I've been playing space engineers which has been epic since they added in-game programming, I'm trying to make a gps auto-pilot navigation script and have to get the block positions finding the blocks by name looking for a smaller string within their bigger string name. I wrote this method to find a small string (word) in a larger string (name of the block):
bool contains(string text, string wordInText)
{
char[] chText = text.ToCharArray();
char[] chWord = wordInText.ToCharArray();
int index = 0;
for(int i = 0 ; i < chText.Length - chWord.Length ; i++)
for(int j = 0; j < chWord.Length;j++,index++)
if (chWord[0] == chText[i])
index = i;
else if (chWord[j] == chText[index]){}
else if (index == chWord.Length-1)
return true;
else break;
return false;
}
Am I even doing it right, should I be doing it another shorter way?
This is simple with .Contains() which returns a bool.
text.Contains(wordInText);
If you simply want to check if a string contains an other string, then you can use string.Contains, the string class already provides a bunch of methods for string operations.
As already mentioned, the String class already has a Contains method that should give you what you need.
That said, your code doesn't work. I can see where you're going with it, but it's just not going to work. Stepping through it in a proper dev environment would show you why, but since this is more in the way of a script that's probably not an option.
So... the basic idea is to iterate through the string you're searching in, looking for matches against the string your searching. Your outer for statement looks fine for this, but your inner statements are a bit messed up.
Firstly, you're doing the first character check repeatedly. It's wasteful, and misplaced. Do it once per iteration of the outer loop.
Second, your exit condition is going to fire when the first character of wordInText matches the characters at index wordInText.Length in text which is not apparently what you want.
In fact you're all tripped up over the index variable. It isn't actually useful, so I'd drop it completely.
Here's a similar piece of code that should work. It is still much slower than the library String.Compare method, but hopefully it shows you how you might achieve the same thing.
for (int i = 0; i <= chText.Length - chWord.Length; i++)
{
if (chText[i] == chWord[0])
{
int j;
for (j = 0; j < chWord.Length; j++)
{
if (chText[i + j] != chWord[j])
break;
}
if (j == chWord.Length)
return true;
}
}
return false;
I have a List of longs from a DB query. The total number in the List is always an even number, but the quantity of items can be in the hundreds.
List item [0] is the lower boundary of a "good range", item [1] is the upper boundary of that range. A numeric range between item [1] and item [2] is considered "a bad range".
Sample:
var seekset = new SortedList();
var skd= 500;
while( skd< 1000000 )
{
seekset.Add(skd, 0);
skd = skd+ 100;
}
If an input number is compared to the List items, if the input number is between 500-600 or 700-800 it is considered "good", but if it is between 600-700 it is considered "bad".
Using the above sample, can anyone comment on the right/fast way to determine if the number 655 is a "bad" number, ie not within any good range boundary (C#, .NET 4.5)?
If a SortedList is not the proper container for this (eg it needs to be an array), I have no problem changing, the object is static (lower case "s") once it is populated but can be destroyed/repopulated by other threads at any time.
The following works, assuming the list is already sorted and both of each pair of limits are treated as "good" values:
public static bool IsGood<T>(List<T> list, T value)
{
int index = list.BinarySearch(value);
return index >= 0 || index % 2 == 0;
}
If you only have a few hundred items then it's really not that bad. You can just use a regular List and do a linear search to find the item. If the index of the first larger item is even then it's no good, if it's odd then it's good:
var index = data.Select((n, i) => new { n, i })
.SkipWhile(item => someValue < item.n)
.First().i;
bool isValid = index % 2 == 1;
If you have enough items that a linear search isn't desirable then you can use a BinarySearch to find the next largest item.
var searchValue = data.BinarySearch(someValue);
if (searchValue < 0)
searchValue = ~searchValue;
bool isValid = searchValue % 2 == 1;
I am thinking that LINQ may not be best suited for this problem because IEnumerable forgets about item[0] when it is ready to process item[1].
Yes, this is freshman CS, but the fastest in this case may be just
// untested code
Boolean found = false;
for(int i=0; i<seekset.Count; i+=2)
{
if (valueOfInterest >= seekset[i] &&
valueOfInterest <= seekset[i+1])
{
found = true;
break; // or return;
}
}
I apologize for not directly answering your question about "Best approach in Linq", but I sense that you are really asking about best approach for performance.
I'm trying to see if when a user enters some text it searches the array for any matches, and whatever doesn't match gets removed from the array;
string search = textBox1.Text;
for (int i = 0; i < staffUsers.Count; i++)
{
if (!(staffUsers[i].staff_name.Contains(search)))
{
staffUsers.Remove(staffUsers[i]);
}
}
I have some rubbish names in my array 'Rob Dob','Joe Bloggs', 'h h', 'ghg hgh', and if the search variable ended up being 'R', Joe Bloggs would get removed but 'h h' and 'ghg hgh' stay there, but there is no R involved there at all? any reason why>?!
You have to iterate backwards in order to remove from an array. Every time you remove an item, your array gets smaller. By going backwards, that fact does not matter.
string search = textBox1.Text;
for (int i = staffUsers.Count - 1; i >= 0 ; i--)
{
if (!(staffUsers[i].staff_name.Contains(search)))
{
staffUsers.Remove(staffUsers[i]);
}
}
The problem with your code is that you are removing items as you iterate over it. You remove an item, but keep iterating, even though the size of the array changes when you remove an item.
You need to reset your i value after you remove something. Alternatively, you need to use a built in to do the heavy lifting:
staffUsers.RemoveAll(i => !(i.staff_name.Contains(search)));
Uses a tiny LINQ expression to do the work. Remove all items where that predicate matches. i represents an item to apply the expression to. If that expression evaluates to true, away it goes.
Long story short, whenever you remove an item at index [i], you skip the item at index [i+1]. For example, if your array looks like:
{'Joe Bloggs', 'Rob Dobb', 'h h', 'gafddf'}; i=0
remove Joe Bloggs, which is at position 0.
{Rob Dobb', 'h h', 'gafddf'}; i=1
remove 'h h', which is at position 1
{Rob Dobb', 'gafddf'}; i=2
i is not less than yourArray.Count, so the loop stops. There is no position 2.
The quickest fix is to add i-- if you remove something from index [i]. In your case,
staffUsers.Remove(staffUsers[i]);
i--;
Hope this helps!
In each iteration of the loop, either remove an item or increment the counter, not both operations. Otherwise, you'll skip the next array element whenever you remove an array element:
string search = textBox1.Text;
for (int i = 0; i < staffUsers.Count;)
{
if (!(staffUsers[i].staff_name.Contains(search)))
{
staffUsers.Remove(staffUsers[i]);
}
else
{
i++;
}
}
The simplest way to solve the above problem is using LINQ.
Following code disentangle above problem.
string search = textBox1.Text;
staffUsers= (from user in staffUsers
where !user.Contains(search)
select user).ToArray<string>();
Note: I assumed staffUsers is array of string.
string search = textBox1.Text;
for (int i = 0; i < staffUsers.Count; i++)
{
if (!(staffUsers[i].staff_name.Contains(search)))
{
staffUsers.Remove(staffUsers[i]);
// reset the index one stepback
i--;
}
}