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11啊哈币
#include <stdio.h>
#include <stdlib.h>
#define MAXOP 100
#define NUMBER '0'
int getop(char []);
void push (double);
double pop(void);
int main()
{
int type;
double op2;
char s[MAXOP];
while ((type=getop(s))!=EOF){
switch(type){
case NUMBER:
push(atof(s));
break;
case '+':
push(pop()+pop());
break;
case '*':
push(pop()*pop());
break;
case '-':
op2=pop();
push(pop()-op2);
break;
case '/':
op2=pop();
if(op2!=0.0)
push(pop()/op2);
else
printf("error:zero divisor\n");
break;
case '\n':
printf("\t%.8g\n",pop());
break;
default:
printf("error:unknown command %s\n",s);
break;
}
}
system("pause");
return 0;
}
#define MAXVAL 100
int sp=0;
double val[MAXVAL];
void push(double f)
{
if (sp<MAXVAL)
val[sp++]=f;
else
printf("error:stack full,can't push %g\n",f);
}
double pop(void)
{
if (sp>0)
return val[--sp];
else{
printf("error:stack empty\n");
return 0.0;
}
}
#include <ctype.h>
int getch(void);
void ungetch(int);
int getop(char s[])
{
int i,c;
while((s[0]=c=getch())==' '||c=='\t')
;
s[i]='\0';
if(!isdigit(c)&&c!='.')
return c;
i=0;
if (isdigit(c))
while(isdigit(s[++i]=c=getch()))
;
if (c=='.')
while(isdigit(s[i++]=c=getch()))
;
s[i]='\0';
if (c!=EOF)
ungetch(c);
return NUMBER;
}
#define BUFSIZE 100
char buf[BUFSIZE];
int bufp=0;
int getch(void)
{
return (bufp>0)?buf[--bufp]:getchar();
}
void ungetch(int c)
{
if (bufp>=BUFSIZE)
printf("ungetch:too many characters\n");
else
buf[bufp++]=c;
}
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