Handling Leading Zeros in CSV Files

John wrote concerning a problem with handling leading zeros in CSV files. He creates CSV files destined for import into an accounting program, but has problems with the CSV files if he needs to first reload the CSV into Excel to correct any mistakes in the file.

Actually, there are two things that need to be checked here. First, is Excel putting the leading zeros in the CSV file it initially creates? Second, is it maintaining the zeros in the CSV file when you reload it and then resave it? These are two separate issues.

You can check the first issue easily enough. All you need to do is rename the CSV file so it has a TXT extension, then you can load it into a text editor, such as Notepad. There you can examine the actual CSV file, as created by Excel, to make sure that everything is in the format you expect. If it is not—for instance, there are no leading zeros where you need them—then you need to be concerned with how Excel is creating the CSV file in the first place.

You need to check whether there are leading zeros in the original Excel information. If there are, and they are displayed, then you need to make sure that the column in which the data is contained is formatted as Text in the Number tab of the Format Cells dialog box. If they are not, then you need to format the cells using a Custom number format that displays the zeros. In both of these cases, the leading zeros will be included in the CSV file created by Excel.

This brings us to the second issue. When you load a CSV file into Excel, it tries to determine the format of the data being loaded. You probably noticed when you loaded your CSV file in Notepad that even though Excel includes leading zeros in the output file, there are no quotes around the field itself. This means that Excel automatically recognizes the field as a number when importing it. By default, then, the number is displayed using one of the number fields, thereby expunging any leading zeros in what Excel displays.

The way around this problem should be fairly obvious based on information earlier in this tip—somehow you need to get Excel to recognize the incoming information as text so that it treats the leading zeros as significant. The quickest way to do this is to follow these steps, prior to loading the CSV file:

1. Make sure the CSV file is renamed so it has a TXT extension. You must perform this step, or the rest of the steps will not work because Excel won't start the Text Import Wizard in step 5.
2. Within Excel, click on the Open tool on the toolbar. Excel displays the Open dialog box. (To display this dialog box in Excel 2007, click the Office button and then click on Open.)
3. Using the Files of Type drop-down list at the bottom of the dialog box, indicate that you want to open Text Files (*.prn; *.txt; *.csv).
4. Select the file you renamed in step 1.
5. Click on Open. Excel starts the Text Import Wizard, displaying the Step 1 of 3 dialog box. (See Figure 1.)



Figure 1. The Text Import Wizard.

6. Make sure the Delimited choice is selected, then click on Next. Excel displays the Step 2 of 3 dialog box.
7. Make sure Comma is selected as a delimiter, then click on Next. Excel displays the Step 3 of 3 dialog box. The interesting thing is that the data in your TXT file should be displayed at the bottom of the dialog box, including any leading zeros in your fields.
8. At the bottom of the dialog box, click on the field that has leading zeros. The entire column should now be selected.
9. In the Column Data Format area, make sure the Text radio button is selected.
10. Repeat steps 8 and 9 for any other fields that have leading zeros.
11. Click on Finish. Your file is imported, with leading zeros still intact.

Now you can do your work in Excel, as desired, and again save your data in CSV format. (You will, however, need to use Save As rather than simply using Save.) The leading zeros will be included in the data that is saved.

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (2588) applies to Microsoft Excel 97, 2000, 2002, and 2003. You can find a version of this tip for the ribbon interface of Excel (Excel 2007 and later) here: Handling Leading Zeros in CSV Files.