From 563cea897121b33cc5e98dc6ed3a36eb39d52766 Mon Sep 17 00:00:00 2001
From: sinanmohd <sinan@firemail.cc>
Date: Sat, 13 May 2023 14:52:00 +0530
Subject: 7.5: initial commit, 4.10 with scanf instead of getchar

---
 7.5/Makefile | 13 +++++++++++++
 7.5/main.c   | 44 ++++++++++++++++++++++++++++++++++++++++++++
 7.5/op.c     | 32 ++++++++++++++++++++++++++++++++
 7.5/op.h     | 10 ++++++++++
 7.5/stk.c    | 29 +++++++++++++++++++++++++++++
 7.5/stk.h    |  7 +++++++
 6 files changed, 135 insertions(+)
 create mode 100644 7.5/Makefile
 create mode 100644 7.5/main.c
 create mode 100644 7.5/op.c
 create mode 100644 7.5/op.h
 create mode 100644 7.5/stk.c
 create mode 100644 7.5/stk.h

diff --git a/7.5/Makefile b/7.5/Makefile
new file mode 100644
index 0000000..43c5a6f
--- /dev/null
+++ b/7.5/Makefile
@@ -0,0 +1,13 @@
+OBJECTS = main.o stk.o op.o
+CC = clang
+CFLAGS = -Wvla -Wall -Wextra -Wstrict-prototypes -Wmissing-prototypes -fsanitize=address
+
+calc : $(OBJECTS)
+	$(CC) $(CFLAGS) -o calc $(OBJECTS)
+
+main.o : stk.h op.h
+
+.PHONY : clean
+
+clean :
+	rm -f calc $(OBJECTS)
diff --git a/7.5/main.c b/7.5/main.c
new file mode 100644
index 0000000..cf5194e
--- /dev/null
+++ b/7.5/main.c
@@ -0,0 +1,44 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "stk.h"
+#include "op.h"
+
+#define MAXOP	100
+
+int main(void)
+{
+	char op[MAXOP];
+	int opd2;
+	int c;
+
+	while ((c = getop(op, MAXOP))) {
+		switch (c) {
+		case NUM:
+			push(atof(op));
+			break;
+		case '+':
+			push(pop() + pop());
+			break;
+		case '-':
+			opd2 = pop();
+			push(pop() + opd2);
+			break;
+		case '*':
+			push(pop() * pop());
+			break;
+		case '/':
+			opd2 = pop();
+			push(pop() / opd2);
+			break;
+		case '\n':
+			printf("\tans: %.2lf\n", pop());
+			clear();
+			break;
+		default:
+			printf("err: unkown operator: %c\n", c);
+			break;
+		}
+	}
+
+	return 0;
+}
diff --git a/7.5/op.c b/7.5/op.c
new file mode 100644
index 0000000..e7640e6
--- /dev/null
+++ b/7.5/op.c
@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <ctype.h>
+#include "op.h"
+
+char getop(char *op, size_t len)
+{
+	size_t i;
+
+	*op = '\0'; // if scanf fails
+	do {
+		scanf("%c", op);
+	} while (isblank(*op));
+
+	if (!isdigit(*op))
+		return *op;
+
+	i = 1;
+	do {
+		scanf("%c", op + i);
+	} while (isdigit(op[i]) && ++i < len);
+
+	if (op[i] == '.') {
+		i++;
+		do {
+			scanf("%c", op + i);
+		} while (isdigit(op[i]) && ++i < len);
+	}
+
+	ungetc(op[i], stdin);
+	op[i] = '\0';
+	return NUM;
+}
diff --git a/7.5/op.h b/7.5/op.h
new file mode 100644
index 0000000..bfe24b5
--- /dev/null
+++ b/7.5/op.h
@@ -0,0 +1,10 @@
+#include <stddef.h>
+
+#ifndef OP_H
+
+#define NUM	'0'
+
+#define OP_H
+#endif
+
+char getop(char *op, size_t len);
diff --git a/7.5/stk.c b/7.5/stk.c
new file mode 100644
index 0000000..ea10221
--- /dev/null
+++ b/7.5/stk.c
@@ -0,0 +1,29 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <error.h>
+#include <errno.h>
+#include "stk.h"
+
+static unsigned top;
+double stk[MAXBUFF];
+
+void push(double n)
+{
+	if (top < MAXBUFF)
+		stk[top++] = n;
+	else
+		error(EXIT_FAILURE, ENOBUFS, "push");
+}
+
+double pop(void)
+{
+	if (top <= 0)
+		error(EXIT_FAILURE, ENOBUFS, "pop");
+
+	return stk[--top];
+}
+
+void clear(void)
+{
+	top = 0;
+}
diff --git a/7.5/stk.h b/7.5/stk.h
new file mode 100644
index 0000000..cd4cf2c
--- /dev/null
+++ b/7.5/stk.h
@@ -0,0 +1,7 @@
+#define MAXBUFF 100
+
+extern double stk[MAXBUFF];
+
+void clear(void);
+void push(double n);
+double pop(void);
-- 
cgit v1.2.3