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formatracket

How to format output using racket

How do I format output using racket? I want to output a fixed-width number and fill it with 0 if the width is too small? How can I do it? I have searched the racket documentation but I can only find fprintf, which seems to be unable to do it.

Solution

  • You can use functions from the racket/format module. For example ~a:

    #lang racket
(require racket/format)
(~a 42 
    #:align 'right
    #:width 4
    #:pad-string "0")

    returns

    "0042"