I want to assign each item of a string list to another string list, like:
stringlist_1 = ("k*k1*k2" , "s*s1*s2" , "b*b1*b2")
I want to make them like this :
stringlist_2 = ("k","k","k2")
stringlist_3 = ("s","s1","s2")
etc..
how can I make that?
I tray to use this code
for (int i=0 ; i<2 ; i++)
{
QStringList d = stringlist_1.value(i).split("*");
qDebug()<< d ;
}
I use a for loop becuase my list it is very big, but
the problem is with storing all strings of primary list in same stringlist (d).
How can I let a for loop change the stringlist which assigned to it in each loop?
Is there another way I could achieve that?
You can create a vector of string lists:
#include <QtCore>
QVector<QStringList> splitTerms(const QStringList & source)
{
QVector<QStringList> result;
result.reserve(source.count());
for (auto src : source)
result.append(src.split(QChar('*'), QString::SkipEmptyParts));
return result;
}
int main() {
qDebug() << splitTerms(QStringList{"k*k1*k2", "s*s1*s2", "b*b1*b2"});
}
Output:
QVector(("k", "k1", "k2"), ("s", "s1", "s2"), ("b", "b1", "b2"))
Can you just split it and assign again?
for (int i=0 ; i<2 ; i++)
{
QStringList d = stringlist_1.value(i).split("*");
qDebug()<< d ;
+ foreach (const QString &s, d) {
+ QStringList dd;
+ dd << s;
+ qDebug() << dd;
+ }
}
Related
I’ve got QTableWidget with data like this:
table.png
The table can contains only names from the QList:
QList<QString> shapes { "Triangle", "Circle", "Trapeze", "Square", "Rectangle", "Diamond" };
with random int values in the neighboring cell.
Table can contain all "shapes" or only a part of it (like in the example).
I try to create separate file for each shape form the table and write down corresponding int values to them.
To achieve this I wrote something like that:
QList<QTableWidgetItem *> ItemList
/.../
for(int i = 0; i < rows; ++i)
{
for(int i = 0; i<columns; ++i)
{
foreach(QString itm, shapes )
{
ItemList = ui->tableWidget->findItems(itm, Qt::MatchExactly);
QFile mFile(itm + ".txt");
if(mFile.open(QFile::ReadWrite))
{
for(int i = 0; i < ItemList.count(); ++i)
{
int rowNR = ItemList.at(i)->row();
int columnNR = ItemList.at(i)->column();
out << "Values = " << ui->tableWidget->item(rowNR, columnNR+1)->text() << endl;
}
}
}
mFile.flush();
mFile.close();
}
}
Files are created for every item from the QList – if the shape from the QList is not in the table, an empty file is created.
How to create files only on the basis of available names in the table?
You can write like this.
QList<QTableWidgetItem *> ItemList
/.../
for(QString str : Shapes){
ItemList = ui->tableWidget->findItems(itm, Qt::MatchExactly); // Get the matching list
if(ItemList.isEmpty(){
continue; // If shape does not exist in table skip the iteration
}
QFile mFile(str + ".txt");
if(!mFile.open(QFile::ReadWrite){
return; // This should not happen ; this is error
}
for(QTableWidgetItem *item : ItemList){
int row = item->row();
int col = item->column()+1; // since it is neighboring cell
QString Value = ui->tableWidget->item(row,col)->text();
mFile.write(Value.toUtf8()); // You can change the way in which values are written
}
mFile.flush();
mFile.close();
}
I'm quite new to C++ and know a little bit about pqxx library. What I want to implement is to prepare statements and bind parameters. In PHP I'm used to doing this in such a nice and concise manner:
$s = $db->prepare("SELECT id FROM mytable WHERE id = :id");
$s->bindParam(':id', $id);
$s->execute();
or using tokens:
$data = array();
$data[] = 1;
$data[] = 2;
$s = $db->prepare("SELECT id FROM mytable WHERE id = ? or id = ?");
$s->execute($data);
I tried to fugure out from pqxx documentation how to implement this, but to me documentation looks like a mess and lacks short and simple examples (like I provided above). I hope someone can also provide such simple examples (or of comparable simplicity - without having to write some behemoth code) when dealing with Postgresql in C++.
A simple example. This just prints the number of entries with id value 0.
#include<pqxx/pqxx>
#include<iostream>
int main()
{
std::string name = "name";
int id = 0;
try {
//established connection to data base
pqxx::connection c("dbname=mydb user=keutoi");
pqxx::work w(c);
//statement template
c.prepare("example", "SELECT id FROM mytable WHERE id = $1");
//invocation as in varible binding
pqxx::result r = w.prepared("example")(id).exec();
w.commit();
//result handling for accessing arrays and conversions look at docs
std::cout << r.size() << std::endl;
}
catch(const std::exception &e)
{
std::cerr << e.what() << std::endl;
return 1;
}
return 0;
}
The function w.prepared() is a bit convoluted. It's similar to a curried(curry) function in haskell, as in it takes a parameter and returns another function which in turn takes another parameter. That kind of thing.
Documentation says:
How do you pass those parameters? C++ has no good way to let you pass an unlimited, variable number of arguments to a function call, and the compiler does not know how many you are going to pass. There's a trick for that: you can treat the value you get back from prepared as a function, which you call to pass a parameter. What you get back from that call is the same again, so you can call it again to pass another parameter and so on.
Once you've passed all parameters in this way, you invoke the statement with the parameters by calling exec on the invocation
If there are more parameters use $1 $2 and so on in the prepare function.
c.prepare("SELECT id name FROM mytable WHERE id = $1 AND name = $2")
and give the varibles as
w.prepared("example")(dollar1_var)(dollar2_var).exec()
An Example for dynamic preparation
#include<pqxx/pqxx>
#include<iostream>
#include<vector>
//Just give a vector of data you can change the template<int> to any data type
pqxx::prepare::invocation& prep_dynamic(std::vector<int> data, pqxx::prepare::invocation& inv)
{
for(auto data_val : data)
inv(data_val);
return inv;
}
int main()
{
std::string name = "name";
//a data array to be used.
std::vector<int> ids;
ids.push_back(0);
ids.push_back(1);
try {
pqxx::connection c("dbname=mydb user=keutoi");
pqxx::work w(c);
c.prepare("example", "SELECT id FROM mytable WHERE id = $1 or id = $2");
pqxx::prepare::invocation w_invocation = w.prepared("example");
//dynamic array preparation
prep_dynamic(ids, w_invocation);
//executing prepared invocation.
pqxx::result r = w_invocation.exec();
w.commit();
std::cout << r.size() << std::endl;
}
catch(const std::exception &e)
{
std::cerr << e.what() << std::endl;
return 1;
}
return 0;
}
if you want to handle other data types use this function definition
template<class T> pqxx::prepare::invocation& prep_dynamic(std::vector<T> data, pqxx::prepare::invocation& inv)
{
for(auto data_val : data)
inv(data_val);
return inv;
}
Use pqxx::prepare::invocation where you can, and bind more values before execution, because it's more stable and error preventative, but there is a faster way as I describe it below.
I.
With invocation:
pqxx::nontransaction W(C);
std::string m_insertCommand = "INSERT INTO tableforperftest(column1, column2) VALUES";
unsigned int m_nCurrentRow = 32767;
for (size_t i = 0; i < m_nCurrentRow; i++)
{
unsigned int countOf$ = i * 2;
for (unsigned int i = 0; i < 2; ++i)
{
if (i == 0)
{
m_insertCommand += "(";
}
else
{
m_insertCommand += ", ";
}
m_insertCommand += "$";
std::stringstream ss;
ss << countOf$ + i + 1;
m_insertCommand += ss.str();
}
if(i < m_nCurrentRow - 1)
m_insertCommand += ") ,";
}
m_insertCommand += ")";
C.prepare("insert_into_db", m_insertCommand);
pqxx::prepare::invocation inv = W.prepared("insert_into_db");
for (size_t i = 0; i < m_nCurrentRow; i++)
{
inv(i)(i);
}
inv.exec();
II.
With stored procedure which gets more values for parameters:
CREATE OR REPLACE FUNCTION insertintoboosted(valuesforinsert TEXT) RETURNS VOID AS
$$
BEGIN
EXECUTE 'INSERT INTO tableforperftestproof(column1, column2) VALUES (' || valuesforinsert || ')';
END;
$$
LANGUAGE plpgsql;
Code:
for (size_t i = 0; i < m_nCurrentRow; i++)
{
if (i == 0)
ss << i << "," << i;
else
ss << "(" << i << "," << i;
if (i < m_nCurrentRow - 1)
ss << "),";
}
C.prepare("prep2", "select insertintoboosted($1::text)");
W.prepared("prep2")(ss).exec();
III.
With parameter bindings and execution for each time:
std::string m_insertCommand3 = "INSERT INTO tableforperftest(column1, column2) VALUES ($1, $2)";
C.prepare("insert_into_db3", m_insertCommand3);
for (size_t i = 0; i < m_nCurrentRow; i++)
{
W.prepared("insert_into_db3")(i)(i).exec();
}
To compare the solutions with 32767 inserts:
Invocation: --> Elapsed: 0.250292s
Stored Proc: --> Elapsed: 0.154507s
Parameter binding + execution each time: --> Elapsed: 29.5566s
std::string output;
if ((checkbox1->isChecked() && checkbox2->isChecked()) &&
(!checkbox3->isChecked() || !checkbox4->isChecked() || !checkbox5->isChecked() || !checkbox6->isChecked()))
{
output = " Using Checkbox: 1, 2 ";
}
if ((checkbox1->isChecked() && checkbox2->isChecked() && checkbox3->isChecked()) &&
(!checkbox4->isChecked() || !checkbox5->isChecked() || !checkbox6->isChecked()))
{
output = " Using Checkbox: 1, 2, 3 ";
}
....
using QT creator how can I verify how many checkboxes have been checked and change the output string accordingly?
with multiple if statements it's not working due to me getting confused with all those NOT AND OR.
and it takes a long time to code all possibilities.
All your checkBoxes should be in groupBox
Try this:
QList<QCheckBox *> allButtons = ui->groupBox->findChildren<QCheckBox *>();
qDebug() <<allButtons.size();
for(int i = 0; i < allButtons.size(); ++i)
{
if(allButtons.at(i)->isChecked())
qDebug() << "Use" << allButtons.at(i)->text()<< i;//or what you need
}
Use an array of checkboxes like this
// h-file
#include <vector>
class MyForm {
...
std::vector< QCheckBox* > m_checkBoxes;
};
// cpp-file
MyForm::MyForm() {
...
m_checkBoxes.push_back( checkbox1 );
m_checkBoxes.push_back( checkbox2 );
...
m_checkBoxes.push_back( checkbox5 );
}
...
output = " Using Checkbox:";
for ( int i = 0, size = m_checkBoxes.size(); i < size; ++i ) {
if ( m_checkBoxes[ i ]->isChecked() ) {
output += std::to_string( i + 1 ) + ", ";
}
}
TLDR: Place them in a container and build your string by iterating over them.
Code:
// line taken from #Chernobyl
QList<QCheckBox *> allButtons = ui->groupBox->findChildren<QCheckBox *>();
auto index = 1;
std::ostringstream outputBuffer;
outputBuffer << "Using Checkbox: ";
for(const auto checkBox: allButtons)
{
if(checkBox->isChecked())
outputBuffer << index << ", ";
++index;
}
auto output = outputBuffer.str();
Use QString instead of std::string and then:
QCheckBox* checkboxes[6];
checkbox[0] = checkbox1;
checkbox[1] = checkbox2;
checkbox[2] = checkbox3;
checkbox[3] = checkbox4;
checkbox[4] = checkbox5;
checkbox[5] = checkbox6;
QStringList usedCheckboxes;
for (int i = 0; i < 6; i++)
{
if (checkbox[i]->isChecked())
usedCheckboxes << QString::number(i+1);
}
QString output = " Using Checkbox: " + usedCheckboxes.join(", ") + " ";
This is just an example, but there's numerous ways to implement this. You could keep your checkboxes in the QList which is a class field, so you don't have to "build" the checkboxes array every time. You could also use QString::arg() instead of + operator for string when you build the output, etc, etc.
What I've proposed is just a quick example.
I am trying to add two items into my QListWidget dynamically. However, the following codes only allow me to add only the last item into the list. strList.size() contains 4 items. Assuming name contains "ABC 1" and "ABC 2".
Is my loop incorrect? Or is my method of adding items into the listWidget wrong?
.h:
public:
QListWidgetItem *item[2];
.cpp:
...
while(!xml.atEnd())
{
xml.readNextStartElement();
if(xml.isStartElement())
{
if(xml.name() == "OS")
{
strList << xml.readElementText();
}
}
}
int num = 0;
for(int i = 0; i < strList.size(); i++)
{
if(strList[i] == "ABC")
{
QString name = strList[i] + strList[i+1];
item[num] = new QListWidgetItem();
item[num]->setText(name);
ui.listWidget->insertItem(num, item[num]);
num += 1;
}
}
Output (listWidget):
ABC02
Expected output (listWidget):
ABC01 ABC02
I'm coding and artificial intelligence using Lua script. And I'd like to push my map in the Lua's stack which is stock in a std::string *. I show you :
My Lua script (just a sketch to display the map) :
function runIa(x, y, map)
table.foreach(map, print)
return 0
end
Which only displays "0" on stdout
Here is where I fill my std::string * :
int AI::update()
{
std::string *map = new std::string[2];
pos_x = 0;
pos_y = 10;
map[0] = "0101100";
map[1] = "1101001";
toot->getGlobal("runIa");
toot->pushPosToScript(pos_x, pos_y);
toot->pushMapToScript(map);
try {
toot->pcall(3, 1, 0);
}
catch (const LuaException & e){
std::cerr << e.what() << std::endl;
}
return 0;
}
And that's how I push it into the Lua's stack :
void Lua::pushMapToScript(std::string *map)
{
lua_newtable(_L);
for (unsigned int i = 0; i < 2; ++i)
{
lua_pushnumber(_L, i + 1);
lua_pushstring(_L, map[i].c_str());
lua_settable(_L, -3);
}
}
It works well for the position but not for the map. I can't display what is store in the var map in the Lua script. Does someone have any idea ?
Thanks a lot.