Question

我希望在for循环中保留变量的三位数。 E.g。

for (int i = 002; i <= 033; i++)
{
      string localFilename = @"\\psf\Home\Pictures\Maulavi\" + i + ".jpg";
      using (WebClient client = new WebClient())
      {
           MessageBox.Show(i.ToString());
           client.DownloadFile("http://eap.bl.uk/EAPDigitalItems/EAP566/EAP566_1_1_19_2-EAP566_Maulvi_January_1946_v43_no2_" + i + "_L.jpg", localFilename);
      }
}

但我改为仅2和3等。我希望它保持为002和003等。我该怎么做？

Answer 1

请尝试DROP PROCEDURE IF EXISTS sp_GetMonthVals; DELIMITER // CREATE PROCEDURE sp_GetMonthVals(IN StartDate DATETIME, IN EndDate DATETIME) BEGIN DECLARE CurrentDate DATETIME; SET @CurrentDate = StartDate; DROP TABLE IF EXISTS _tmpMonthVals; CREATE TABLE _tmpMonthVals (`MDate` DATETIME, `DVal` int); label1: WHILE @CurrentDate < EndDate DO INSERT INTO _tmpMonthVals SELECT @CurrentDate, DVal FROM Table1 WHERE MDate <= @CurrentDate ORDER BY MDate DESC LIMIT 1; SET @CurrentDate = DATE_ADD(@CurrentDate, INTERVAL 1 DAY); END WHILE label1; SELECT * FROM _tmpMonthVals; END// DELIMITER ; CREATE TABLE IF NOT EXISTS Table1 (`id` int, `MDate` DATETIME, `DVal` int) ; INSERT INTO Table1 (`id`, `MDate`, `DVal`) VALUES (1, '2015-10-17', 25), (2, '2015-10-12', 20), (3, '2015-10-01', 5); CALL sp_GetMonthVals('2015-10-01', '2015-10-31');，如下所示：

ToString("000")

Answer 2

您可以i.ToString("D3")或i.ToString("000")。

有关数字到字符串转换的更多信息，请查看Standard Numeric Format Strings。

Answer 3

使用函数ToString()的重载格式化字符串：

for(int i = 2; i <= 33; i++)
{
    string localFilename = @"\\psf\Home\Pictures\Maulavi\" + i.ToString("000") + ".jpg";
}

或者您可以使用Format功能：

String.Format("{0:000}", i);

Answer 4

使用string.Format（@“\ psf \ Home \ Pictures \ Maulavi {0：000} .jpg”，i）

格式也将比字符串连接具有更好的性能。

Answer 5

请按照以下方式使用：

        char padChar = '0';
        for (int i = 002; i <= 033; i++)
        {
            string localFilename = @"\\psf\Home\Pictures\Maulavi\" + i + ".jpg";
            string padStr = i.ToString().PadLeft(3,padChar);
            using (WebClient client = new WebClient())
            {
                MessageBox.Show(i.ToString());
                client.DownloadFile("http://eap.bl.uk/EAPDigitalItems/EAP566/EAP566_1_1_19_2-EAP566_Maulvi_January_1946_v43_no2_" + padStr + "_L.jpg", localFilename);
            }
        }

有关此次访问的详情，请访问：http://mahedee.net/padding-character-with-string/

如何在for循环中保留变量的位数

5 个答案: