How to Output a File in Ruby
Ruby has a variety of ways which make it simple to output a file, depending on what you want to do with the data already in the file. There are also a number of methods for writing to the open file. Here are some fairly compact ways of , including some shortcuts, to output a file in Ruby.
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Instructions
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Open and Write to the File in Ruby
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Open the file you wish to output.
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Use the File.open method and pass the filename and a "mode string." The mode string should be either "w" or "a."
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Using "w" will delete all data already in the file. Using "a," will append any data you write to the file to the end of that file.
Print Data
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Print formatted data with the printf method. If you need to write a sequence of numbers or strings, the printf method and format strings are a powerful tool in Ruby.
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Choose one of the many options that go beyond simply printing a string or integer. The argument to print is called a "format string." It consists of the string you want printed, with a number of codes inside that will be expanded.
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For example, using "This is a number: %d," will print the string "This is a number: " and then a decimal number.
Close the File
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Close the file using the close method. Call the close method, or the file might never be closed:
f = File.open("myfile.txt", "r")
# ... Do something with the file
f.close -
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Use a method to automatically close the file if you don't need it open for long. The File.open method can take a block as an argument.
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If you pass a block, the file will automatically be closed at the end of the block.
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Tips & Warnings
Be sure you understand what a block is. Every single time the loop is run in Ruby, a piece of code known as a block is executed.
