The MFC CComboBox allows a person to do an AddString of an empty string. I just proved that by doing a GetCount() before and another after the AddString; Count was 0, then it became 1; and the GUI also seems to reflect it, as its list was an huge empty box, and when adding it became a one-liner.
I also proved it further by doing
int a = m_combo.GetCount();
CString sx= _T("Not empty string");
if(a == 1)
m_combo.GetLBText(0, sx);
TRACE(_T("Start<%s>End"), sx);
and the Output window displays
File.cpp(9) : atlTraceGeneral - Start<>End
so we conclude the sx variable is empty.
Then I do a FindString having a CString m_name variable which is empty:
int idx= m_combo.FindString(-1, m_name);
And it returns CB_ERR!
Is it standard behavior for empty string entries? Official documentation doesn't say anything about it!
If it is, what is the simplest way to override it? Is there some parameter or change in the resources to change the behaviour? If there is not, I am thinking about deriving or composing a class just for the case where the string is Empty!
I did it manually for the empty string and it works!
CString sItem;
int idx_aux= CB_ERR;
// need it because FindString, FindStringExact and SelectSring return CB_ERR when we provide an empty string to them!
if(m_name.IsEmpty())
{
for (int i=0; i<m_combo.GetCount(); i++)
{
m_combo.GetLBText(i, sItem);
if(sItem.IsEmpty())
{
idx_aux= i;
break;
}
}
}
else
idx_aux= m_combo.FindString(-1, m_name);
Related
import java.util.Scanner;
class Palindrome_string
{
public static void main()
{
System.out.println("\f");
Scanner sc = new Scanner(System.in);
System.out.println("Enter a string");
String a = sc.nextLine();
int b = a.length();
String rev = "";
for (int i = b - 1; i >= 0; i--)
{
char c = a.charAt(i);
rev = rev + c;
}
System.out.println("Original word "+a);
System.out.println("Reversed word "+rev);
a = a.toLowerCase();
rev = rev.toLowerCase();
if (a == rev)
{
System.out.println("It is a palindrome");
}
else
{
System.out.println("It is not a palindrome");
}
sc.close();
}
}
The program compiles properly. Still, when running the program, the message which tells if it is a palindrome prints incorrectly. What changes do I make? Here is a picture of the output. Even though the word 'level' (which is a palindrome) has been inputted, it shows that it isn't a palindrome. What changes should I make? output pic
You should not use == to compare two strings because it compares the reference of the string, i.e. whether they are the same object or not.
Use .equals() instead. It tests for value equality. So in your case:
if (a.equals(rev))
{
System.out.println("It is a palindrome");
}
Also try not to use single-letter variable names except for index variables when iterating over a list etc. It's bad practice.
Redirect me if this is already a previously solved issue!
In my program, I have a Stage in which the user can view a list of content, stored in a list consisting of Strings.
goToView.setOnAction(event ->{
menuStage.close();
viewStage.show();
String horseNameList = "";
for(int i = 0; i < accountList.size(); i++){
if(accountList.get(i).userName.equals(uName)){
for(int j = 0; j < accountList.get(i).createdHorses.size(); j++){
horseNameList += accountList.get(i).createdHorses.get(j);
horseNameList += "\n" + "\n";
}
}
Text hNameListTXT = new Text(horseNameList);
hNameListTXT.setFont(Font.font("Tahoma", FontWeight.NORMAL, 12));
listVbox.getChildren().add(hNameListTXT);
}
createdHorses is a List of Strings, listVbox is as you may think a VBox where the String (which converts to a Text) is printed. Now, when I close the Stage with the following EventHandler, nothing in particular happens:
backView.setOnAction(event -> {
viewStage.close();
menuStage.show();
});
But as I then open the Stage once again (by using another EventHandler similar to the one I use to close the first Stage with), my List (or String) har been doubled. What should I do to clear the String (or possibly the Text) so that it doesn't display it twice?
What should I do to clear the String (or possibly the Text) so that it
doesn't display it twice?
The VBox has a method getChildren() which returns an ObservableList. So you could use clear() on it to remove all the children.
As an assignment we are supposed to create methods that copy what string methods do. We are just learning methods and I understand them, but am having trouble getting it to work.
given:
private String st = "";
public void setString(String p){
st = p;
}
public String getString(){
return st;
}
I need to create public int indexOf(char index){}, and public String substring(int start, int end){} I've succesfuly made charAt, and equals but I need some help. We are only allowed to use String methods charAt(), and length(), and + operator. No arrays or anything more advanced either. This is how I'm guessing you start these methods:
public int indexOf(char index){
for(int i = 0; i < st.length(); i++){
return index;
}
return 0;
}
public String substring(int start, int end){
for(int i = 0; i < st.length(); i++){
}
return new String(st + start);
}
thanks!
here's my two working methods:
public boolean equals(String index){
for(int a = 0; a < index.length() && a < st.length(); a++){
if(index.charAt(a) == st.charAt(a) && index.length() == st.length()){
return true;
}
else{
return false;
}
}
return false;
}
public char charAt(int index){
if(index >= 0 && index <= st.length() - 1)
return st.charAt(index);
else
return 0;
}
For your indexOf method, you're on the right track. You'll want to modify the code in the loop. Since you're looping through the whole String, and you only have two methods available, which will help you most to get the characters from the String? Look to your other methods (equals and charAt) to see how you did them, it might give a hint. Remember, you want find a single character in your String and print out the index in which you found it.
For your substring method what you need to do is get all the characters that are represented beginning at start index and go up until end index. A loop is a good start, but you will need a base String to hold your progress in (you will need an empty String). The beginning and end point of your loop need a looking at. For substring, you want to get everything starting at start and everything before end. For instance, if I do the following:
String myString = "Racecar";
String sub = myString.substring(1, 4);
System.out.println(sub);
I should get the output ace.
I would give you the answer, but I think helping guide your reasoning will give you more benefit. Enjoy your assignment!
Trying to implement my first Parallel::For loop with a tread local variable to sum results of the loop. My code is based on an example listed in "Visual C++ 2010, by W. Saumweber, D. Louis (German). Ch. 33, P.804).
I get stuck in the implementation with syntax errors in the Parallel::For call. The errors are as follows, from left to right: a) expected a type specifier, b) too many arguments for generic class "System::Func", c) pointer to member is not valid for a managed class, d) no operator "&" matches these operands.
In line with the book, I create a collection with data List<DataStructure^> numbers, which is subject to a calculation performed in method computeSumScore which is called by the Parallel::For routine in method sumScore. All results are summed in method finalizeSumScore using a lock.
Below I paste the full code of the .cpp part of the class, to show what I have. The data collection "numbers" may look a bit messy, but that's due to organical growth of the program and me learning as I go along.
// constructor
DataCollection::DataCollection(Form1^ f1) // takes parameter of type Form1 to give acces to variables on Form1
{
this->f1 = f1;
}
// initialize data set for parallel processing
void DataCollection::initNumbers(int cIdx)
{
DataStructure^ number;
numbers = gcnew List<DataStructure^>();
for (int i = 0; i < f1->myGenome->nGenes; i++)
{
number = gcnew DataStructure();
number->concentrationTF = f1->myOrgan->cellPtr[cIdx]->concTFA[i];
number->stringA->AddRange(f1->myGenome->cStruct[i]->gString->GetRange(0, f1->myGenome->cChars));
number->stringB->AddRange(f1->myGenome->cStruct[i]->pString);
if (f1->myGenome->cStruct[i]->inhibitFunc)
number->sign = -1;
else
number->sign = 1;
numbers->Add(number);
}
}
// parallel-for summation of scores
double DataCollection::sumScore()
{
Parallel::For<double>(0, numbers->Count, gcnew Func<double>(this, &GenomeV2::DataCollection::initSumScore),
gcnew Func<int, ParallelLoopState^, double, double>(this, &GenomeV2::DataCollection::computeSumScore),
gcnew Action<double>(this, &GenomeV2::DataCollection::finalizeSumScore));
return summation;
}
// returns start value
double DataCollection::initSumScore()
{
return 0.0;
}
// perform sequence alignment calculation
double DataCollection::computeSumScore(int k, ParallelLoopState^ status, double tempVal)
{
int nwScore;
if (numbers[k]->concentrationTF > 0)
{
nwScore = NeedlemanWunsch::computeGlobalSequenceAlignment(numbers[k]->stringA, numbers[k]->stringB);
tempVal = Mapping::getLinIntMapValue(nwScore); // mapped value (0-1)
tempVal = (double) numbers[k]->sign * tempVal * numbers[k]->concentrationTF;
}
else
tempVal = 0.0;
return tempVal;
}
// locked addition
void DataCollection::finalizeSumScore(double tempVal)
{
Object^ myLock = gcnew Object();
try
{
Monitor::Enter(myLock);
summation += tempVal;
}
finally
{
Monitor::Exit(myLock);
}
}
Once this problem is solved I need to ensure that the functions called (computeGlobalSequenceAlignment and getLinIntMapvalue) are thread safe and the program doesn't get stalled on multiple treads accessing the same (static) variables. But this needs to work first.
Hope you can help me out.
Hans Passant answered my question in the comments (include full method name, add comma). Yet I cannot mark my question as answered, so this answer is to close the question.
I am look for the combobox to display 4 rows where the first row shows "a", 2nd row shows "b"..."c"..."d"
cb1 = new CComboBox;
cb1->Create( WS_VSCROLL | CBS_DROPDOWN | WS_VISIBLE | WS_BORDER, CRect(20,200,200, 300), this, 30 );
CString itemSet[] = {"a","b","c","d"};
//I am to set the array all at once with out doing each itme ??
cb1.AddString(itemSet); //fails
There's no function to do so in one go. You could do as Jeeva suggest, a simple loop traversing your array:
CString itemSet[] = {"a","b","c","d"};
for (int i = 0; i < _countof(itemSet); ++i)
{
cb1.AddString(itemSet[i]);
}
However, if you are going to use it often, you could create your own CCombobox derived class and add a function that does it.
class CMyCombo : public CCombobox
{
public:
CMyCombo();
void AddStrings(const CString* strings, int num);
// ...
}
void CMyCombo::AddStrings(const CString* strings, int num)
{
for (int i = 0; i < num; ++i)
{
cb1.AddString(strings[i]);
}
}
Actually, I would probably use a container, such as std::vector or CStringArray, but you get the idea.
By the way, if you are using strings that could be localized, you should not rely on strings only. A better approach can be found here.
One last thing: there's usually no need to create controls on the fly. It's usually easier to create member variables for them.
Do something like this
CString arr[2] = {_T("A"),_T("B")};
for(int i =0 ;i <2; i++)
{
m_ctrlCombo.AddString(arr[i]);
}