calc_adv.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <ctype.h>
   4 #include <math.h>
   5
   6 #define MAXOP 100
   7 #define NUMBER '0'
   8 #define MAXVAL 100
   9 #define BUFSIZE 100
  10
  11 void dup_stack(void);
  12 int getop(char[]);
  13 void push(double);
  14 double pop(void);
  15 void print_stack(void);
  16 void reverse(void);
  17 int getch(void);
  18 void ungetch(int);
  19
  20 char buf[BUFSIZE];
  21 int bufp = 0;
  22 int sp = 0;
  23 double val[MAXVAL];
  24 static int ungetchar = '\0';
  25
  26 int main()
  27 {
  28         int type;
  29         double op2;
  30         char s[MAXOP];
  31
  32         while((type = getop(s)) != EOF)
  33         {
  34                 switch(type)
  35                 {
  36                         case NUMBER:
  37                                 push(atof(s));
  38                                 break;
  39                         case '#':
  40                                 dup_stack();
  41                                 break;
  42                         case '?':
  43                                 print_stack();
  44                                 break;
  45                         case '~':
  46                                 reverse();
  47                                 break;
  48                         case '+':
  49                                 push(pop() + pop());
  50                                 break;
  51                         case '*':
  52                                 push(pop() * pop());
  53                                 break;
  54                         case '-':
  55                                 op2 = pop();
  56                                 push(pop() - op2);
  57                                 break;
  58                         case '/':
  59                                 op2 = pop();
  60                                 if(op2 != 0.0)
  61                                         push(pop() / op2);
  62                                 else
  63                                         printf("error: zero divisor\n");
  64                                 break;
  65                         case '%':
  66                                 op2 = pop();
  67                                 if(op2 != 0.0)
  68                                 {
  69                                         push((int)(pop()) % (int)(op2));
  70                                 } else {
  71                                         printf("error: zero divisor\n");
  72                                 }
  73                                 break;
  74                         case 'c':
  75                                 push(cos(pop()));
  76                                 break;
  77                         case 'p':
  78                                 push((int)pow(pop(),pop()));
  79                                 break;
  80                         case 't':
  81                                 push(tan(pop()));
  82                                 break;
  83                         case 'q': // square root
  84                                 push(sqrt(pop()));
  85                                 break;
  86                         case 'r':
  87                                 push(rand());
  88                                 break;
  89                         case 's':
  90                                 push(sin(pop()));
  91                                 break;
  92                         case '\n':
  93                                 printf("\t%.8g\n", pop());
  94                                 break;
  95                         default:
  96                                 printf("error: unknown command %s\n", s);
  97                                 break;
  98                 }
  99         }
 100         return 0;
 101 }
 102
 103 /* push f onto value stack */
 104 void push(double f)
 105 {
 106         if(sp < MAXVAL)
 107                 val[sp++] = f;
 108         else
 109                 printf("error: stack full\n");
 110 }
 111
 112 /* pop and return top value from stack */
 113 double pop(void)
 114 {
 115         if(sp > 0)
 116                 return val[--sp];
 117         else
 118         {
 119                 printf("stack empty\n");
 120                 return 0.0;
 121         }
 122 }
 123
 124 /* duplicate value at top of stack */
 125 void dup_stack()
 126 {
 127         int temp = pop();
 128         push(temp);
 129         push(temp);
 130 }
 131
 132 /* reverse two vales at top of stack */
 133 void reverse()
 134 {
 135         double temp1, temp2;
 136         temp1 = pop();
 137         temp2 = pop();
 138         push(temp1);
 139         push(temp2);
 140 }
 141
 142 /* print top two values on stack */
 143 void print_stack()
 144 {
 145         if(sp > 0)
 146                 printf("%f\t%f\n", val[sp], val[sp-1]);
 147         // else
 148                 // printf("Stack is empty!\n");
 149 }
 150
 151 /* get next operator or numberic operand */
 152 int getop(char s[])
 153 {
 154         int i, c;
 155
 156         while ((s[0] = c = getch()) == ' ' || c == '\t')
 157                 ;
 158         s[1] = '\0';
 159         if(!isdigit(c) && c != '.')
 160                 return c;
 161         i = 0;
 162         if(isdigit(c))
 163                 while(isdigit(s[++i] = c = getch()))
 164                         ;
 165         if(c == '.')
 166                 while(isdigit(s[++i] = c = getch()))
 167                         ;
 168         s[i] = '\0';
 169         if(c != EOF)
 170                 c = ungetchar;
 171         return NUMBER;
 172 }
 173
 174 int getch(void)
 175 {
 176         return (bufp > 0) ? buf[--bufp] : getchar();
 177 }
 178
 179 /* NO LONGER NEEDED
 180 void ungetch(int c)
 181 {
 182         if(bufp >= BUFSIZE)
 183                 printf("ungetch: too many characters\n");
 184         else
 185                 buf[bufp++] = c;
 186 }
 187 */