How the Import Wizard Determines the Text File Type

• Microsoft Visual FoxPro for Windows, version 3.0

SUMMARY

The Import Wizard assists you in creating a FoxPro table from another type of file, such as a text file. This article explains how FoxPro determines the type (fixed-length, comma-delimited, or tab-delimited) of text file you are importing.

MORE INFORMATION

Determining Records to Analyze

When you import a text file using the Import Wizard, by default it reads the first 50 records in the text file. To begin analysis at a different row, or perform analysis on all records, choose the Options button in the "Step 1a - Options" screen of the Import Wizard.

NOTE: The analysis of records cannot be manually interrupted.

Determining File Type

The following tests are performed in the order listed to determine the file's type:

1. Do all records have the same length? If true, this is a fixed-length file.

2. Do all records have the same number of commas? If true, this is a comma-delimited file.

3. Do all records have the same number of tabs? If true, this is a tab-delimited file.

4. Do all records have the same number of semicolons? If true, this is a semicolon-delimited file.

5. If none of the previous tests are true, the Import Wizard assumes the file to be a fixed-length file, using the length of the longest record in the 50-record sample as the record length.

Determining File Structure

Once the file's type is determined, the following tests are performed to determine its structure.

• Fixed-length Files: Each record is analyzed to determine potential column breaks, by tracking the locations in each record where a space is followed by a non-space character. When 75% or more of the records have this transition from a space to non-space character in the same location, that location is assumed to be a column break. This is how the Import Wizard decides where to place the default column breaks displayed in Step 1a.
• Delimited Files: Each field in all records is analyzed to determine the maximum field lengths. All fields are assumed to be character unless a field is wider than the maximum character field width, in which case the field is assumed to be a memo field.