查找最小日期/用途和最大日期/用途

Question

I am in need of some assistance. I have an XML bill that has multiple same Nodes. right now im looping through the nodes and merging the values accordingly. The code I am showing you is only the part i need help with. The loop contains a lot more where i am merging values together. What I need help is with choosing the MIN and MAX dates/usages. Since I am returning multiple nodes instead of one now i will loop and merge the data.

1. So after it loops through the nodes i need the UsageMeterReadStartDate to be set to the earliest MIN date. dataType string
2. Same thing with UsageMeterReadStartUsage. dataType string
3. So after it loops through the nodes i need the UsageMeterReadStartDate to be set to the latest MAX date. dataType string
4. same with UsageMeterReadEndUsage

That is what I am stuck on. I have already finished merging all of the other data i need. I am 18yrs old and a pretty new programmer. I'm just getting lost in my own logic. Any guidance would help me out. I beleive The last two IF statements is where i need help and where the logic would go.

Answer 1

I think what you want to do is loop through all of the items first. Convert these to a DateTime object. The DateTime object lets you compare others for greater than or less than. I think though, you'll get caught up in year transitions because you're not tracking that in the source.

if (meterReadStartXMLNodes.Count > 0 && meterReadStartXMLNodes[0].HasChildNodes)
{   // This is to fill up the meter read start date and meter read start usage as an attribute of the "sadetails" node in the newer XML. 
    DateTime oldDateTime = DateTime.Now;
    string oldUsage = "";
    foreach (var node in meterReadStartXMLNodes)
    {
        DateTime tempDateTime = DateTime.Parse(String.Format("{0} {1}", meterReadStartXMLNodes[0].SelectSingleNode("IRBILGU_US_USG_STRT_DT_MM.USAGE").InnerText,
                                                                        meterReadStartXMLNodes[0].SelectSingleNode("IRBILGU_US_USG_STRT_DT_DD.USAGE").InnerText));

        if (tempDateTime < oldDateTime)
        {
            // Any time you've determined you have an older date, we capture the usage for that date
            oldDateTime = tempDateTime;
            oldUsage = meterReadStartXMLNodes[0].SelectSingleNode("IRBILGU_US_KWH_PRV_MTR_READ.USAGE").InnerText;
        }
    }

    // By the time you get here, you've already determined the lowest date/time, format it.
    saBillDetail.UsageMeterReadStartDate = oldDateTime.ToString("MMM dd");
    saBillDetail.UsageMeterReadStartUsage = oldUsage;
}

For the end dates you sort of do the same thing, except don't need to assign it a value, it will default to like year 0001.

if (meterReadEndXMLNodes.Count > 0 && meterReadEndXMLNodes[0].HasChildNodes)
{   // This is to fill up the meter read end date and meter read end usage as an attribute of the "sadetails" node in the newer XML.

    DateTime latestDateTime = new DateTime();
    string latestUsage = "";
    foreach (var node in meterReadStartXMLNodes)
    {
        DateTime tempDateTime = DateTime.Parse(String.Format("{0} {1}", meterReadStartXMLNodes[0].SelectSingleNode("IRBILGU_US_USG_END_DT_MM.USAGE").InnerText,
                                                                        meterReadStartXMLNodes[0].SelectSingleNode("IRBILGU_US_USG_END_DT_DD.USAGE").InnerText));

        if (tempDateTime > latestDateTime)
        {
            // Any time you've determined you have an newer date, we capture the usage for that date
            latestDateTime = tempDateTime;
            latestUsage = meterReadStartXMLNodes[0].SelectSingleNode("IRBILGU_US_KWH_MTR_READ.USAGE").InnerText;
        }
    }

    saBillDetail.UsageMeterReadEndDate = latestDateTime.ToString("MMM dd");
    saBillDetail.UsageMeterReadEndUsage = latestUsage;
}

Granted, I didn't test this stuff, but it should get you going and you can fix the bugs. Since you're new to programming, do you understand what I've done?