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POQt Setting table entry changes value of QMap
 

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  1. POQt Setting table entry changes value of QMap
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    <p>I have an issue with a "table->setItem(index, 0, widg);" statement having unwanted side-effects.</p> <p>I have a map of QStrings to QStrings:</p> <pre><code>QMap&lt;QString, QString&gt; levelPlist; </code></pre> <p>Later on, I have a function to fill a QTableWidget with the keys and values contained in this map. So, I have the following function:</p> <pre><code>void MainWindow::updateLevelPlistTable() { QTableWidget *table = ui-&gt;levelPlistTableWidget; int count = levelPlist.count(); table-&gt;setRowCount(count); table-&gt;setColumnCount(2); QMap&lt;QString, QString&gt;::const_iterator i; int index = 0; for (i = levelPlist.constBegin(); i != levelPlist.constEnd(); ++i) { qDebug(QString("BG TEX pre - " + levelPlist.value("background_texture")).toAscii()); QTableWidgetItem *widg = new QTableWidgetItem(i.key()); qDebug(QString("BG TEX pre mid - " + levelPlist.value("background_texture")).toAscii()); table-&gt;setItem(index, 0, widg); qDebug(QString("BG TEX mid - " + levelPlist.value("background_texture")).toAscii()); table-&gt;setItem(index, 1, new QTableWidgetItem(i.value())); qDebug(QString("BG TEX post - " + levelPlist.value("background_texture")).toAscii()); if(index == 0) { qDebug(QString("Key - " + i.key() + ", Value - " + i.value()).toAscii()); } index++; } } </code></pre> <p>Pardon all of the debugging text, but that's how I was able to narrow down exactly where the problem is. Here's some of the output from when the function runs ("background_texture" initially maps to "nope"):</p> <pre> BG TEX pre - nope BG TEX pre mid - nope BG TEX mid - background_texture BG TEX post - background_texture Key - background_texture, Value - background_texture BG TEX pre - background_texture BG TEX pre mid - background_texture BG TEX mid - level_height BG TEX post - 600 BG TEX pre - 600 BG TEX pre mid - 600 BG TEX mid - level_width BG TEX post - 400 </pre> <p>As you can see, the value changes between the "pre mid" and "mid" debug statements, which means that executing the statement of "table->setItem(index, 0, widg);" changes the value of the "background_texture" key to whatever the latest i.value() is.</p> <p>Why?</p> <p>Edit: Full debug information: </p> <pre><code>void MainWindow::updateLevelPlistTable() { QTableWidget *table = ui-&gt;levelPlistTableWidget; int count = levelPlist.count(); table-&gt;setRowCount(count); table-&gt;setColumnCount(2); QMap&lt;QString, QString&gt;::const_iterator i; int index = 0; for (i = levelPlist.constBegin(); i != levelPlist.constEnd(); ++i) { QTableWidgetItem *widg = new QTableWidgetItem(i.key()); table-&gt;setItem(index, 0, widg); qDebug() &lt;&lt; "before - " &lt;&lt; levelPlist; table-&gt;setItem(index, 1, new QTableWidgetItem(i.value())); qDebug() &lt;&lt; "after - " &lt;&lt; levelPlist &lt;&lt; "\n"; index++; } } </code></pre> <p>produces </p> <pre><code>before - QMap(("background_texture", "background_texture")("level_height", "600")("level_width", "400")("start_x", "250")("start_y", "50")("world", "null")) after - QMap(("background_texture", "background_texture")("level_height", "600")("level_width", "400")("start_x", "250")("start_y", "50")("world", "null")) before - QMap(("background_texture", "level_height")("level_height", "600")("level_width", "400")("start_x", "250")("start_y", "50")("world", "null")) after - QMap(("background_texture", "600")("level_height", "600")("level_width", "400")("start_x", "250")("start_y", "50")("world", "null")) before - QMap(("background_texture", "level_width")("level_height", "600")("level_width", "400")("start_x", "250")("start_y", "50")("world", "null")) after - QMap(("background_texture", "400")("level_height", "600")("level_width", "400")("start_x", "250")("start_y", "50")("world", "null")) before - QMap(("background_texture", "start_x")("level_height", "600")("level_width", "400")("start_x", "250")("start_y", "50")("world", "null")) after - QMap(("background_texture", "250")("level_height", "600")("level_width", "400")("start_x", "250")("start_y", "50")("world", "null")) before - QMap(("background_texture", "start_y")("level_height", "600")("level_width", "400")("start_x", "250")("start_y", "50")("world", "null")) after - QMap(("background_texture", "50")("level_height", "600")("level_width", "400")("start_x", "250")("start_y", "50")("world", "null")) before - QMap(("background_texture", "world")("level_height", "600")("level_width", "400")("start_x", "250")("start_y", "50")("world", "null")) after - QMap(("background_texture", "null")("level_height", "600")("level_width", "400")("start_x", "250")("start_y", "50")("world", "null")) </code></pre>
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    1. COInteresting. What does qDebug() << levelPList before and after the iteration say?
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      1. USFrank Osterfeld
 

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