A filehandle is a variable that is used to read and write to a file. This filehandle gets associated with the file.
In order to write to the file, it is opened in write mode as shown below:
open (FH, ‘>’, “filename.txt”);
If the file is existing then it truncates the old content of file with the new content. Otherwise a new file will be created and content will be added.
print() function
print() function is used to write content to a file.
Syntax: print filehandle string
Here, filehandle is associated to the file at the time of opening the file and string holds the content to be written to the file.
Example :
Before Writing to File:
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Executing Code to Write:
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Updated File:
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Here is how the program works:
Step 1: Opening file Hello.txt in write mode.
Step 2: Getting the text from the standard input keyboard.
Step 3: Writing the string stored in '$a' to the file pointed by filehandle 'fh'
Step 4: Closing the file.
Copying Content from one file to another:
Before Code Execution:
Source File:
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Destination File:
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Example :
Example below reads the content from the source file and writes it to destination file.
Executing Code:
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Updated Destination File:
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Here is how the program works:-
Step 1: Opening 2 files Source.txt in read mode and Destination.txt in write mode.
Step 2: Reading the content from the FHR which is filehandle to read content while FHW is a filehandle to write content to file.
Step 3: Copying the content with the use of print function.
Step 4: Close the conn once reading file is done.
Error Handling and Error Reporting
There are two ways in which Errors can be handled
- Throw an exception if file cannot be opened (Handling an error)
- Give a warning if file cannot be opened and continue running (Error reporting)
Throw an Exception (Using Die Function)
When filehandle could not be assigned a valid file pointer at that time die gets executed printing the message and kills the current program.
Example :
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In the above code when File exists it simply gets executed with no errors but if file doesn't exists then it generates an error and code terminates.
Give a warning (Using warn function)
When filehandle could not be assigned a valid file pointer it just prints warning message using warn function and keeps running.
Example :
When File exists:
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When File doesn't exists:
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