trouble recognizing \ as a character-CodePudding

I'm making a syntax analyzer for school that reads a c test file in scheme and outputs another in html with the program now colored based on their id. However, I'm having trouble with it recognizing the \ as a character. The teacher said we don't have to worry about respecting the formatting, so line breaks and indents aren't necessary. Here is my code as well as the test file:

#lang racket

(require 2htdp/batch-io)

;shortcuts
(define htmlformat "<!DOCTYPE html> <html> <head> <link rel='stylesheet' href='styles.css'> <title>output.html</title> </head> <body>")
(define htmlformat2 "</body> </html>")
(define number "<span class='number'>")
(define specials "<span class='special'>")
(define ids "<span class='identifier'>")
(define reserved "<span class='reserved'>")
(define comments "<span class='comment'>")
(define libraries "<span class='library'>")
(define endspan "</span>")

;opens input file
(define infile "test.cpp")

;read input file
;char by char
(define file->list-of-chars
  (lambda (filename)
    (flatten
     (map string->list
          (read-1strings filename)))))

;char to strings, shows up in reverse order
(define list-of-chars->list-of-strings
  (lambda (loc aux result)
    (cond
      [(empty? loc) result]
      [(char-whitespace? (car loc))
       (list-of-chars->list-of-strings (cdr loc)
                                       '()
                                       (cons
                                        (list->string aux)
                                        result))]
      [(char-punctuation? (car loc))
       (list-of-chars->list-of-strings (cdr loc)
                                       '()
                                       (cons
                                        (list->string
                                         (cons (car loc) '()))
                                        (cons
                                         (list->string aux)
                                         result)))]
      [else
       (list-of-chars->list-of-strings (cdr loc)
                                       (append aux (cons (car loc) '()))
                                       result)])))

; char to list of strings, shows up in corret order
(define file->list-of-strings
  (lambda (filename)
    (reverse
     (list-of-chars->list-of-strings
      (file->list-of-chars infile) '() '()))))

(define lst (file->list-of-strings infile))

;regex matching
(define match
  (λ (strng)
    (cond
      [(regexp-match #rx"^[ -]?([0-9] \\.?[0-9]*|\\.[0-9] )$" strng) (string-append number strng endspan)]
      [(equal? strng "<iostream>") (string-append libraries "<" endspan libraries "iostream" endspan libraries ">" endspan)] 
      [(regexp-match #rx"^\\<(.) \\>$" strng) (string-append libraries "strng" endspan)]
      [(regexp-match #rx"^(asm|double|new|switch|auto|else|operator|template|break|enum|private|this|case|extern|printf|protected|throw|catch|float|public|try|char|for|register|typedef|class|friend|return|union|const|goto|short|unsigned|continue|if|signed|virtual|default|inline|sizeof|void|delete|int|static|volatile|do|long|struct|while) $" strng) (string-append reserved strng endspan)]
      [(regexp-match #rx"^([A-Z]|[a-z]|\\_)(.)*$" strng) (string-append ids strng endspan)]
      [(regexp-match #rx"^(\\#|\\[|\\]|\\{|\\}|\\ |\\-|\\/|\\<|\\>|\\<=|\\>=|\\=|\\(|\\)|\\*|\\'|\\;|\\!|\\$|\\%|\\^|\\&|\\?|\"|\\||,)$" strng) (string-append specials strng endspan)]
      [(regexp-match #rx"^\\//(.)*$" strng) (string-append comments strng endspan)]
      [else ""])))

;applies match to all elements of a list of strings
(define mapp
  (λ (lst)
    (cond
      [(null? lst) '()]
      [else (cons (match (car lst))(mapp (cdr lst)))])))

;assigns html format to list of strings
(define htmlList (mapp lst))

; list of strings to single string
(define list-of-strings->string
  (lambda (strlst)
    (string-join strlst " ")))
;; usage example
;; (define strlst (file->list-of-strings input-filename))
;; (list-of-strings->string strlst)

; converts list of strings to a single string
(define singlestring (list-of-strings->string htmlList))

;creates output file
(define outfile "output.html")

;creates single string adding html header and footer
(define finalstring (string-append htmlformat singlestring htmlformat2))

;writes everything into output file
(write-file outfile finalstring)

Test code:

#include <iostream>

int main(int argc, char *argv[])
{
    int i = 0;

    for (i = 0; i < 10; i  )
    {
        printf("%i", i);
    }
    printf("\n");
    return 0;
}

CodePudding user response：

What do you mean "recognize \"?

You can "escape the escape code" by using "\\"

printf("\\");

That should print "\".

If you want to print 2, you can do printf("\\\\")... it goes on.

Other than that, I don't understand your question.

CodePudding user response：

Use

[(char-whitespace? (car loc))
 ...]
[(eqv? (car loc) #\\)
 ...]

to recognize backslash.

Note: #\a means the character a and thus #\\ means the character \.