How to use string interpolation in foreach loop ?

Question

Hi All,
Please help me to format the string with 'string Interpolation'. Below is my foreach loop code with string + concatenation. I want to avoid + concatenation and use 'string Interpolation'

        int itemsCount = oUpdateVarList.Count();
        int loopCount = 0;
        foreach (string oVarItem in oUpdateVarList)
        {
            loopCount++;
            string[] oArrList = oVarItem.Split(new[] { oEngineContext.colDelimiter }, StringSplitOptions.RemoveEmptyEntries);

            if (loopCount != itemsCount)
            {
                query += oArrList[1] + " : '" + oArrList[3].ToString() + "',";
            }
            else
            {
                query += oArrList[1] + " : '" + oArrList[3].ToString()+ "'}) return id(a)"; 
            }

        }

Answer 1

@Binumon George , you could try the following code to use string interpolation to replace string + concatenation.

   int itemsCount = list.Count();  
    int loopCount = 0;  
    string query = string.Empty;  
    foreach (string oVarItem in list)  
    {  
        loopCount++;  
        string[] oArrList = oVarItem.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);  
  
        if (loopCount != itemsCount)  
        {  
            query=$"{query}{oArrList[1]}: '{oArrList[3].ToString()}',";  
       
        }  
        else  
        {  
            query=$"{query}{oArrList[1]}: '{oArrList[3].ToString()}'}}) return id(a)";  
        }  
    }  

Based on my test, I can get the same result with the code you provided.

Best Regards,
Jack

---

If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Answer 2

You just need to add a $ before your string, then you can embed your variable between { and }:

int itemsCount = oUpdateVarList.Count();
int loopCount = 0;
foreach (string oVarItem in oUpdateVarList) {
    loopCount++;
    string[] oArrList = oVarItem.Split(new[] { oEngineContext.colDelimiter }, StringSplitOptions.RemoveEmptyEntries);

    if (loopCount != itemsCount) {
        query += $"{oArrList[1]} : '{oArrList[3]}',";
    } else {
        query += $"{oArrList[1]} : '{oArrList[3]}'}}) return id(a)";
    }
}

Notice that if you have any literal brace characters in your string then you have to escape them by double them up, i.e. } becomes }} to let the compiler know that it's not an interpolated variable.

Also variables that you embed in an interpolated string are automatically .ToString()'d (so does string.Format too actually) so you can avoid adding those in.