From 7fa502ba4e60ce762ab529996c66a1a831cb789f Mon Sep 17 00:00:00 2001
From: Martin Ashby <martin@ashbysoft.com>
Date: Mon, 21 Nov 2022 21:28:36 +0000
Subject: Switch getch implementation for getline instead

---
 ex4-3.c | 129 ++++++++++++++++++++++++----------------------------------------
 1 file changed, 49 insertions(+), 80 deletions(-)

diff --git a/ex4-3.c b/ex4-3.c
index ca5739a..78e0944 100644
--- a/ex4-3.c
+++ b/ex4-3.c
@@ -1,9 +1,10 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <ctype.h>
+#include <string.h>
 
 #define NUMBER '0'
-#define MAXOP 100
+#define MAXLINE 1000
 #define MAXVAL 100
 
 int getop(char[]);
@@ -22,48 +23,54 @@ double frem(double f1, double f2) {
  * Reverse polish notation calculator
  */
 int main(void) {
-    int type;
     double op2;
-    char s[MAXOP];
-    while ((type = getop(s)) != EOF) {
-        switch (type) {
-            case NUMBER:
-                push(atof(s));
-                break;
-            case '+':
-                push(pop() + pop());
-                break;
-            case '*':
-                push(pop() * pop());
-                break;
-            case '-':
-                op2 = pop();
-                push(pop() - op2);
-                break;
-            case '/':
-                op2 = pop();
-                if (op2 != 0.0)
-                    push(pop() / op2);
-                else
-                    printf("error: zero division attempted!\n");
-                break;
-            case '%':
-                op2 = pop();
-                if (op2 != 0.0) 
-                    push(frem(pop(), op2));
-                else 
-                    printf("error: zero division attempted!\n");
-                break;
-            case '~':
-                clear();
-            case '\n':
-                printf("\t%.8g\n", peek());
-                break;
-            default:
-                printf("unknown command %s\n", s);
-                break;
-        }
+    char* line = NULL;
+    size_t line_len = 0;
+    while (getline(&line, &line_len, stdin) != -1) {
+        char* tok = strtok(line, " ");
+        do {
+            int type = getop(tok);
+            switch (type) {
+                case NUMBER:
+                    push(atof(tok));
+                    break;
+                case '+':
+                    push(pop() + pop());
+                    break;
+                case '*':
+                    push(pop() * pop());
+                    break;
+                case '-':
+                    op2 = pop();
+                    push(pop() - op2);
+                    break;
+                case '/':
+                    op2 = pop();
+                    if (op2 != 0.0)
+                        push(pop() / op2);
+                    else
+                        printf("error: zero division attempted!\n");
+                    break;
+                case '%':
+                    op2 = pop();
+                    if (op2 != 0.0) 
+                        push(frem(pop(), op2));
+                    else 
+                        printf("error: zero division attempted!\n");
+                    break;
+                case '~':
+                    clear();
+                    break;
+                default:
+                    //printf("unknown command %s\n", tok); // Just ignore it?
+                    break;
+            }
+        } while ((tok = strtok(NULL, " ")) != NULL);
+
+        printf("\t%.8g\n", pop());
     }
+    free(line); // or, don't bother since we exit the program next...
+    
     return 0;
 }
 
@@ -99,47 +106,9 @@ void clear(void) {
     sp = 0;
 }
 
-int getch(void);
-void ungetch(int);
-
 int getop(char s[]) {
-    int i,c;
-    // Skip to teh first non-space or tab character
-    while ((s[0] = c = getch()) == ' ' || c == '\t');
-    // Then add a null for some reason?
-    s[1] = '\0';
-    // if it's not a part of a number, it's an operation
+    char c = s[0];
     if (!isdigit(c) && c != '.') 
         return c;
-    // Integer part
-    i = 0;
-    if (isdigit(c)) 
-        while (isdigit(s[++i] = c = getch()));
-    // fraction part
-    if (c == '.')
-        while (isdigit(s[++i] = c = getch()));
-    s[i] = '\0';
-    if (c != EOF) 
-        ungetch(c);
     return NUMBER;
 }
-
-#define BUFSIZE 100
-
-int buf = -2;
-
-int getch(void) {
-    if (buf != -2) {
-        int z = buf;
-        buf = -2;
-        return z;
-    }
-    return getchar();
-}
-
-void ungetch(int c) {
-    if (buf != -2) 
-        printf("ungetch: buffer full\n");
-    else
-        buf = c;
-}
\ No newline at end of file
-- 
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