From a34e1ed98dd2dd22721f2dd6fa5af06f771b403a Mon Sep 17 00:00:00 2001
From: Sadeep Madurange <smadurange@users.noreply.github.com>
Date: Fri, 10 Dec 2021 19:41:31 +0800
Subject: 4.4

---
 4/4.c | 36 +++++++++++++++++++++++-------------
 4/5.c |  1 -
 2 files changed, 23 insertions(+), 14 deletions(-)

(limited to '4')

diff --git a/4/4.c b/4/4.c
index a1e99e2..b6b194d 100644
--- a/4/4.c
+++ b/4/4.c
@@ -4,6 +4,7 @@
 
 #define MAXOP 100  /* max size of operand or operator */
 #define NUMBER '0' /* signal that a number was found */
+#define COP '1'    /* signal that a custom op was found */
 #define MAXVAL 100 /* max depth of val stack */
 #define BUFSIZE 100
 
@@ -28,8 +29,8 @@ double peek();
 /* clears the stack */
 void clear();
 
-/* adds commands p (print top val without popping), c (duplicate top val), s
- * (swap top two stack positions), d (clear stack) */
+/* adds commands peek (print top val without popping), dup (duplicate top val),
+ * swap (swap top two stack positions), clear (clear stack) */
 int main(int argc, char *argv[]) {
   int type;
   double op2, op1;
@@ -130,29 +131,38 @@ void ungetch(int c) {
 }
 
 int getop(char s[]) {
-  int i, c;
+  int i, c, rv;
 
   while ((s[0] = c = getch()) == ' ' || c == '\t')
     ;
   s[1] = 0;
 
-  if (!isdigit(c) && c != '.' && c != '-')
+  // operators or line feed
+  if (c == '\n' || c == '+' || c == '*' || c == '/' || c == '%')
     return c;
 
   i = 0;
-  if (isdigit(c))
-    while (isdigit(s[++i] = c = getch()))
-      ;
-  if (c == '.')
-    while (isdigit(s[++i] = c = getch()))
-      ;
-  if (c == '-')
-    while (isdigit(s[++i] = c = getch()))
+
+  // numbers
+  if (isdigit(c) || c == '-') {
+    if (c == '-') {
+      // minus operator
+      if (!isdigit(s[++i] = c = getch())) {
+        ungetch(c);
+        s[i] = 0;
+        return '-';
+      }
+    }
+
+    while (isdigit(s[++i] = c = getch()) || c == '.')
       ;
+    rv = NUMBER;
+  }
+
   s[i] = 0;
 
   if (c != EOF)
     ungetch(c);
 
-  return NUMBER;
+  return rv;
 }
diff --git a/4/5.c b/4/5.c
index 0516783..83c44e6 100644
--- a/4/5.c
+++ b/4/5.c
@@ -1,4 +1,3 @@
-
 #include <ctype.h>
 #include <math.h>
 #include <stdio.h>
-- 
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