命令行参数问题
#include<stdio.h>#include<math.h>
#include<stdlib.h>
#include<ctype.h>
#define MAXOP 100
#define NUMBER '0'
int getop(char []);
void push(double);
double pop(void);
void ungetch(char []);
main(int argc, char *argv[])
{
double op2;
char s[MAXOP];
while(--argc > 0)
{
ungetch(" ");
ungetch(*++argv);
switch(getop(s)){
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;
default:
printf("error: unkown command %s\n",s);
argc = 1;
break;
}
}
printf("\t%.8g\n", pop());
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;
}
}
int getop(char s[])
{
int i,c;
while((s[0] = c = getch()) == ' '||c == '\t')
;
s[1] = '\0';
if(!isdigit(c) && c != '.' && c != '-')
return c;
i = 0;
if(c == '-')
{
if(isdigit(c = getch())||c == '.')
s[++i] = c;
else
{
if(c!=EOF)
ungetch(c);
return '-';
}
}
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;
void ungetch(char a[])
{
int i = 0;
if(bufp >= BUFSIZE)
printf("unget: too many charaters\n");
else
buf[bufp++] = a[i];
}
为什么我的程序没有输出结果？
