[diskcontroller] increase readability

diff --git a/src/lib/elm_diskcontroller.c b/src/lib/elm_diskcontroller.c
index 4ebd278..2ea9766 100644 (file)
--- a/src/lib/elm_diskcontroller.c
+++ b/src/lib/elm_diskcontroller.c
@@ -220,9 +220,9 @@ static int check_letter(const char *str, int length)
        int code = str[length];\r
 \r
        if(code == '\0') return length; // null string\r
-       else if((code >= 65 && code <= 90) || (code >= 97 && code <= 122)) return length; // alphabet\r
-    else if (48<=code && code<58) return length; // number\r
-    else if ((33<=code && code<47) || (58<=code && code<64) || (91<=code && code<96) || (123<=code && code<126)) return length; // special letter\r
+       else if((code >= 'A' && code <= 'Z') || (code >= 'a' && code <= 'z')) return length; // alphabet\r
+       else if ('0'<=code && code<='9') return length; // number\r
+       else if ((33<=code && code<47) || (58<=code && code<64) || (91<=code && code<96) || (123<=code && code<126)) return length; // special letter\r
 \r
        return length-1;\r
 }\r