Fixed negative number issue

src/ee.h

@@ -0,0 +1,36 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <ctype.h>
+#include <string.h>
+
+
+const int ERR_NS_OPERANDS       = 1;
+const int ERR_NS_OPERATORS      = 2;
+const int ERR_INVALID_INPUT     = 4;
+const int ERR_INVALID_FACTORIAL = 8;
+
+
+struct EE_STACK_NODE {
+    double datum;
+    struct EE_STACK_NODE* tail;
+};
+typedef struct EE_STACK_NODE NODE;
+typedef struct EE_STACK_NODE* STACK;
+
+void   push(double,STACK*);
+void   pop(STACK*);
+double  peek(STACK*);
+
+int     isNum(const char*);
+int     arrity(const char);
+
+double  evaluate(STACK*, char);
+double* operands(STACK*, int);
+double  fact(int n);
+
+void    report(STACK*,char*);
+
+
+
+