C] A operate B 형 사칙연산 계산기

	#include <stdio.h>
	#include <ctype.h>
	#include <stdlib.h>
	#define MAXLINE 100
	void read_in(char s[]);
	int calc(char *s);
	int main()
	{
	char line[MAXLINE];
	read_in(line);
	printf("Result = %d\n", calc(line));
	return 0;
	}
	void read_in(char s[])
	{
	int c, i=0;
	printf("Input an equation: ");
	while ((c=getchar()) != '\n')
	s[i++]=c;
	s[i]='\0';
	}
	int calc(char *s)
	{
	int num1=0, num2=0, ret;
	char c, op;
	c=*s++;
	while (isdigit(c))
	{
	num1=10*num1+(c-'0');
	c=*s++;
	}
	op=c;
	c=*s++;
	while (isdigit(c))
	{
	num2=10*num2+(c-'0');
	c=*s++;
	}
	switch (op)
	{
	case '+' :
	ret = num1+num2;
	break;
	case '-' :
	ret = num1-num2;
	break;
	case '*' :
	ret = num1*num2;
	break;
	case '/' :
	ret = num1/num2;
	break;
	default:
	printf("error: unknown operator %c\n", op);
	exit(1);
	}
	return ret;
	}

view raw gistfile1.c hosted with ❤ by GitHub

num1 op num2 만 계산되므로,

stack 를 이용한 infix to postfix 를 적용한 후,

깔삼한 계산기를 두들겨 볼까,,