When working with dates in Excel, it is important to be aware of the potential for automatic date parsing. This can occur when a date is entered into a cell that is formatted as text, or when a date is imported from another source. Automatic date parsing can cause problems because Excel may interpret the date incorrectly, or it may change the format of the date. To avoid these problems, you can use the DATEVALUE function to explicitly convert a text string to a date value. This function takes a text string as an argument and returns the equivalent date value. For example, if the text string "1/2/2015" is entered into a cell, the DATEVALUE function will return the date value "2-Jan-2015".
To use the DATEVALUE function, select a cell and enter =DATEVALUE(A1), where A1 is the cell containing the text string. The result of the function will be displayed in the selected cell. You can also use the DATEVALUE function to convert a date to a different format. For example, if you want to display a date as "January 2, 2015", you can use the TEXT function with the DATEVALUE function: =TEXT(DATEVALUE("1/2/2015"),"mmmm d, yyyy").
It is also possible to defeat automatic date parsing by using quotation marks around a date when it is entered into a cell. For example, if you enter "1/2/2015" into a cell without quotation marks, Excel will automatically parse it as a date and convert it to "2-Jan-2015". However, if you enter "1/2/2015" into a cell with quotation marks, Excel will treat it as text and will not automatically parse it as a date.
In summary, automatic date parsing can cause problems in Excel because dates can be interpreted incorrectly or converted to a different format. To avoid these problems, you can use the DATEVALUE function to explicitly convert text strings to dates. You can also use quotation marks around dates to prevent them from being automatically parsed.