QString strValue = "3.14159"; double dblValue = strValue.toDouble();
QString strValue = "invalid"; bool bOk = false; double dblValue = strValue.toDouble(&bOk); if (!bOk) { // Handle error }In this example, the QString object "strValue" contains an invalid value. The toDouble function is called on this object, and the returned value is stored in the "dblValue" variable. However, since the value is invalid, the "bOk" variable is set to false. This can be used to handle errors gracefully. The QString class is part of the Qt library.