Merge pull request #262 from xexyl/1994-shapiro-eof

Fix EOF == -1 assumption in 1994/shapiro

1994/shapiro/README.md

@@ -10,17 +10,21 @@ USA
 
         make all
 
-[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) pointed out a potential
-bug on systems where `EOF != -1`. The problem is that `getc()` and the related
-functions do not return `-1` on EOF or error but rather `EOF` but the program
-assumes `-1` (conversely when using the `getopt()` functions one should not
-check for EOF but -1 as the functions return -1 not EOF but the standard does
-not require `EOF` to be -1, just a negative number. However changing it to check
-for `!=EOF` caused a problem due to the clever encoding of the code. See
-[bugs.md](/bugs.md) for more details if you wish to try and fix this (Cody is
-here and there working on it along with other things and will change this
-message when it's fixed assuming it's feasible).
-
+[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) fixed a bug on systems
+where `EOF != -1`. The problem is that `getc()` and the related functions do not
+return `-1` on EOF or error but rather `EOF`. However `EOF` is not required to be
+`-1` but merely an int < 0 and this program assumed that `getc()` will return
+`-1` on EOF or error, not `EOF`. On systems where `EOF != -1` it could be a
+problem. For the same reason one should not use `EOF` for the `getopt()`
+functions as they return `-1` when all options are parsed (for details on the
+definition of `EOF` see `7.21 Input/output<stdio.h>` subsection 1 of the
+standard). An interesting problem occurred where changing the `-1` to `EOF`
+caused both `warning: illegal character encoding in string literal` and `error:
+source file is not valid UTF-8`. But since `EOF` is simply an int < 0 and making
+the loop condition check that the return value is >= 0 does not cause a
+compilation error and it functions correctly it will address the systems where
+`EOF != -1` just as if it checked for `!= EOF`. Thank you Cody for your
+assistance!
 
 ## To run:
 

1994/shapiro/shapiro.c

@@ -11,7 +11,7 @@
           /*T*/,"r");for      (;(       L/*KPUOWOWMUQ
          LLOLMPULWLWL         WLW         LWLWLWLWLWLW
          LWLWLULVOXP          LLV          LLLOLMPULOL
-        MMNP*/=getc           (J)            )!= -1;L/*
+        MMNP*/=getc           (J)            )>= 0;L/*
        OLWLRMMQUL             VOX             PLLVLLLMQO
        PMPYPXPNP              MQL              LVLLLWPSP
       XPOQNQOPMQ              LLV              LTj*/>='J'

1994/shapiro/shapiro.md

@@ -13,7 +13,7 @@ This is a very simple program:
  5. FILE *J;
  6. J=fopen(__FILE__,"r");
  7. for(;
- 8.     (L=getc(J))!=EOF;
+ 8.     (L=getc(J))>=0;
  9.     L>='J'&&L<='J'+15 && 
 10.     ((M=!M)?K=L:putchar(K-'J'|(L-'J'<<4)))
 11.    );