教程：C++ 调试

本教程使用TextFinder示例来说明如何在Debug 模式下调试 Qt C++ 应用程序。

TextFinder 将文本文件读入QString ，然后用QTextEdit 显示。查看 TextFinder 类并查看存储的数据：

在 textfinder.cpp 中，单击改变光标位置的那一行的行号和窗口边框之间的位置，以设置断点。
转到Debug >Start Debugging >Start Debugging of Startup Project 或选择F5。
要查看有关断点的信息，请转到Breakpoints 视图。
要删除断点，请右键单击该断点并选择Delete Breakpoint 。
要查看 TextFinder 类的基类和数据成员，请转到Locals 视图。

修改on_findButton_clicked() 函数，使其返回到文档的起始位置，并在光标到达文档末尾时继续搜索。添加以下代码段：

void TextFinder::on_findButton_clicked()
{
    QString searchString = ui->lineEdit->text();

    QTextDocument *document = ui->textEdit->document();
    QTextCursor cursor = ui->textEdit->textCursor();
    cursor = document->find(searchString, cursor,
        QTextDocument::FindWholeWords);
    ui->textEdit->setTextCursor(cursor);

    bool found = cursor.isNull();

    if (!found && previouslyFound) {
        int ret = QMessageBox::question(this, tr("End of Document"),
        tr("I have reached the end of the document. Would you like "
        "me to start searching from the beginning of the document?"),
        QMessageBox::Yes | QMessageBox::No, QMessageBox::Yes);

        if (ret == QMessageBox::Yes) {
            cursor = document->find(searchString,
                QTextDocument::FindWholeWords);
            ui->textEdit->setTextCursor(cursor);
        } else
            return;
    }
    previouslyFound = found;
}

但是，如果编译并运行上述代码，由于逻辑错误，应用程序无法正常运行。要找出这个逻辑错误，请使用以下按钮逐步查看代码： (Stop Debugger)、 (Step Over)、 (Step Into)和走出去 (Step Out)。

另请参阅 教程：Qt Widgets 应用程序、调试、调试器和调试器。

教程如何

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