When it comes to managing files in Delphi, one common task is to retrieve the create and last modified dates of a specific file. This information can be useful for various purposes, such as tracking changes or organizing files based on their creation date. In this article, we will explore how to get these dates using Delphi's built-in functions.
To begin with, let's create a new Delphi project and add a button to the form. We will use this button to trigger our code and display the result. Next, we need to add the "SysUtils" unit to our uses clause. This unit contains the necessary functions to retrieve file information.
Now, let's take a look at the "FileAge" function. This function takes in a file name as a parameter and returns the last modified date of the file. For example, if we have a file named "myFile.txt" in our project directory, we can get its last modified date using the following code:
```delphi
var
fileName: string;
lastModified: TDateTime;
begin
fileName := 'myFile.txt';
lastModified := FileAge(fileName);
ShowMessage(DateTimeToStr(lastModified));
end;
```
This code will display the last modified date of the "myFile.txt" file in a message box. However, if we want to get the creation date instead, we need to use the "FileDate" function. This function also takes in a file name as a parameter, but it returns the creation date of the file instead of the last modified date.
Now, what if we want to get both the create and last modified dates of a file? In that case, we can use the "FileAge" function and specify the desired date type as a second parameter. For example, if we want to get the creation date, we can use the following code:
```delphi
var
fileName: string;
createDate: TDateTime;
begin
fileName := 'myFile.txt';
createDate := FileAge(fileName, faCreation);
ShowMessage(DateTimeToStr(createDate));
end;
```
Similarly, if we want to get the last modified date, we can use "faLastWrite" as the second parameter. It's worth noting that the "FileAge" function returns a "TDateTime" value, which represents the date and time in Delphi. If we want to display it in a more readable format, we can use the "DateTimeToStr" function, as shown in the code snippets above.
In addition to the above methods, Delphi also provides the "FileDateTime" function, which returns a "TDateTime" value representing the last modified date of the file. This function takes in a file name as a parameter, just like the "FileAge" function. However, it differs in the way it handles the date type. Instead of specifying it as a second parameter, we need to use the "FileSetDate" function to set the desired date type before calling "FileDateTime". For example:
```delphi
var
fileName: string;
lastModified: TDateTime;
begin
fileName := 'myFile.txt';
FileSetDate(fileName, faLastWrite);
lastModified := FileDateTime(fileName);
ShowMessage(DateTimeToStr(lastModified));
end;
```
This code will first set the date type to "faLastWrite" and then retrieve the last modified date of the file. This method can be useful when we want to get the date for a specific type without changing the default date type.
In conclusion, retrieving the create and last modified dates of a file in Delphi is a straightforward process. We can use the "FileAge" and "FileDateTime" functions to get these dates, and we can specify the desired date type using the "faCreation" and "faLastWrite" constants. With this knowledge, you can now easily track file changes and manage them efficiently in your Delphi applications.
