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#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <math.h>
#define MAXOP 100
#define NUMBER_SIG '0'
double pop(void);
void push(double f);
char getop(char str[]);
int
main(void)
{
char str[MAXOP];
char type;
double op2;
while ((type = getop(str)) != EOF) {
switch (type) {
case NUMBER_SIG :
push(atof(str));
break;
case '+' :
push(pop() + pop());
break;
case '*' :
push(pop() * pop());
break;
case '-' :
op2 = pop();
push(pop() - op2);
break;
case '/' :
if ((op2 = pop()) == 0.0)
printf("Err: deviser cant be zero\n");
else
push(pop() / op2);
break;
case '%' :
op2 = pop();
if (op2 != 0)
push(fmod(pop(), op2));
else
printf("Err: deviser cant be zero\n");
break;
case '\n' :
printf("%.8g\n", pop());
break;
default :
printf("Err: unknown command\n");
}
}
return 0;
}
#define MAXVAL 100
double val[MAXVAL];
int sp = 0;
double
pop(void)
{
if (sp > 0)
return val[--sp];
else {
printf("Err: stack empty\n");
return 0.0;
}
}
void
push(double f)
{
if (sp < MAXVAL)
val[sp++] = f;
else
printf("Err: stack is full\n");
}
char getch(void);
void ungetch(char input);
char
getop(char str[])
{
char input;
int i;
/* ignore blanks */
while ((input = str[0] = getch()) == ' ' || input == '\t');
/* return operator */
if (!isdigit(input) && input != '.')
return input;
/* collect digits*/
for (i = 1; i < MAXOP && (isdigit(input=getch()) || input == '.'); i++)
str[i] = input;
str[i] = '\0';
if (input != EOF)
ungetch(input);
return NUMBER_SIG;
}
#define MAXBUFF 100
char buff[MAXBUFF];
int bp = 0;
char
getch(void)
{
return (bp > 0) ? buff[--bp] : getchar();
}
void
ungetch(char input)
{
if (bp < MAXBUFF)
buff[bp++] = input;
else {
printf("Err: buffer full\n");
}
}
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