102 lines
1.3 KiB
C
Executable file
102 lines
1.3 KiB
C
Executable file
#include <stdio.h>
|
|
#include <ctype.h>
|
|
|
|
#define MAXOP 40
|
|
#define NUMBER '0'
|
|
#define STACKSIZE 40
|
|
|
|
UBYTE sp;
|
|
WORD stack[STACKSIZE];
|
|
|
|
char s[MAXOP];
|
|
UBYTE pos;
|
|
WORD n;
|
|
|
|
void push(WORD l)
|
|
{
|
|
if(sp < STACKSIZE)
|
|
stack[sp++] = l;
|
|
else
|
|
puts("Stack full");
|
|
}
|
|
|
|
WORD pop(void)
|
|
{
|
|
if(sp > 0)
|
|
return stack[--sp];
|
|
else
|
|
puts("Stack empty");
|
|
return 0;
|
|
}
|
|
|
|
WORD top(void)
|
|
{
|
|
if(sp > 0)
|
|
return stack[sp-1];
|
|
else
|
|
puts("Stack empty");
|
|
return 0;
|
|
}
|
|
|
|
BYTE read_op(void)
|
|
{
|
|
if(pos == 0) {
|
|
gets(s);
|
|
}
|
|
|
|
while(s[pos] == ' ' || s[pos] == '\t')
|
|
pos++;
|
|
|
|
if(s[pos] == '\0') {
|
|
pos = 0;
|
|
return('\n');
|
|
}
|
|
|
|
if(!isdigit(s[pos]))
|
|
return(s[pos++]);
|
|
|
|
n = s[pos] - '0';
|
|
while(isdigit(s[++pos]))
|
|
n = 10 * n + s[pos] - '0';
|
|
|
|
return NUMBER;
|
|
}
|
|
|
|
void main(void)
|
|
{
|
|
BYTE type;
|
|
WORD op2;
|
|
|
|
puts("RPN Calculator");
|
|
sp = 0;
|
|
pos = 0;
|
|
|
|
while((type = read_op()) != 0) {
|
|
switch(type) {
|
|
case NUMBER:
|
|
push(n);
|
|
break;
|
|
case '+':
|
|
push(pop() + pop());
|
|
break;
|
|
case '*':
|
|
push(pop() * pop());
|
|
break;
|
|
case '-':
|
|
op2 = pop();
|
|
push(pop() - op2);
|
|
break;
|
|
case '/':
|
|
op2 = pop();
|
|
if(op2 != 0)
|
|
push(pop() / op2);
|
|
else
|
|
puts("Divide by 0");
|
|
break;
|
|
case '\n':
|
|
printf("==> %d\n", top());
|
|
break;
|
|
}
|
|
}
|
|
}
|