Ruby read file with block

Add a comment. Active Oldest Votes. The easiest way if the file isn't too long is: puts File. Suits my case perfectly. This is hardly idiomatic Ruby. Be wary of "slurping" files. That's when you read the entire file into memory at once.

I like to use: IO. This is exactly what I was looking for. I've got a file with five million lines, and really didn't want that loaded into memory. I wonder why is file "slurping" called like that? According this dictionary slurp means "To eat or drink noisily". It comes from programming history. Here's a starting point perl. Use foreach instead. I usually use the Sublime Text editor, with the RubyMarkers plugin, when documenting code to be used in answers here.

It makes it really easy to show intermediate results, similar to using IRB. Great answer. For the last example I might suggest using while instead of loop and using ensure to ensure the file gets closed even if an exception is raised.

As with read or any variant, this will pull the entire file into memory, which can cause major problems if the file is larger than the memory available. A block is always invoked from a function with the same name as that of the block. This means that if you have a block with the name test , then you use the function test to invoke this block. Here, you will learn to invoke a block by using a simple yield statement.

You will also learn to use a yield statement with parameters for invoking a block. You will check the sample code with both types of yield statements. Here, the yield statement is written followed by parameters. You can even pass more than one parameter. This code will pass the contents of the file test line by line to the variable block, and then the output will be displayed on the screen. You can rename and delete files programmatically with Ruby with the rename and delete methods. Following is the example to change mode of an existing file test.

All files are contained within various directories, and Ruby has no problem handling these too. Whereas the File class handles files, directories are handled with the Dir class. To change directory within a Ruby program, use Dir. You can get a list of the files and directories within a specific directory using Dir. The Dir. Temporary files are those that might be created briefly during a program's execution but aren't a permanent store of information.

To make Dir. You can use Dir. This code creates a temporary file, writes data to it, and deletes it. File Class and Methods. Dir Class and Methods. Eduonix Learning Solutions. Programming Line. Previous Page. Next Page. Live Demo. In the below example we are opening a file with the help of the keyword call new. In new we are opening the file with the read mode like File. In the below example we are using a simple open keyword to read file contents. We can explain the below code in the following steps.

In the below example we are using a split keyword to read file contents. Here we are writing a simple code to print each line of the file because in the below example we have taken only one line of the sentence so that the first line has been printed. In this example, we are simply performing the looping on the test.