qt c++ 实现一个函数，输入的参数为Qstring，实现每一天调用qDebug()<<"day"；考虑闰年平年和大小月，范围为某年某月某日到某年某月某日，并计算总的天数

好的，根据你的要求，这里提供一个输入参数为QString类型的函数实现，该函数实现了每一天调用qDebug()<<"day"，并考虑了闰年平年和大小月，范围为某年某月某日到某年某月某日，并计算总天数。代码如下：

#include <QtCore>

int daysInMonth(int year, int month) {
    if (month == 2) {
        if (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0)) {
            return 29;
        } else {
            return 28;
        }
    } else if (month == 4 || month == 6 || month == 9 || month == 11) {
        return 30;
    } else {
        return 31;
    }
}

int daysBetween(QString startDateStr, QString endDateStr) {
    QDate startDate = QDate::fromString(startDateStr, "yyyy-MM-dd");
    QDate endDate = QDate::fromString(endDateStr, "yyyy-MM-dd");
    int days = 0;
    for (int year = startDate.year(); year <= endDate.year(); ++year) {
        int startMonth = (year == startDate.year() ? startDate.month() : 1);
        int endMonth = (year == endDate.year() ? endDate.month() : 12);
        for (int month = startMonth; month <= endMonth; ++month) {
            int startDay = (year == startDate.year() && month == startDate.month() ? startDate.day() : 1);
            int endDay = (year == endDate.year() && month == endDate.month() ? endDate.day() : daysInMonth(year, month));
            for (int day = startDay; day <= endDay; ++day) {
                qDebug() << "day";
                ++days;
            }
        }
    }
    return days;
}

int main(int argc, char *argv[]) {
    QCoreApplication app(argc, argv);

    QString startDateStr = "2020-01-01";
    QString endDateStr = "2020-01-31";
    int totalDays = daysBetween(startDateStr, endDateStr);
    qDebug() << "Total days:" << totalDays;

    return app.exec();
}

这个程序中，我们定义了一个输入参数为QString类型的函数daysBetween，该函数实现了从起始日期到结束日期的天数计算，并在每个日期上调用qDebug()<<"day"。在main函数中，我们可以设置起始日期和结束日期的字符串，并调用daysBetween函数来计算总天数。