C++表达式计算器

Question

用C语言 设计一个表达式计算器，通过键盘输入表达式。能够按照括号和基本四则运算法则计算出该表达式的值

Answer 1

#include <stdio.h>

int result=0,valuess=0,k,y=1,l;
char a,b[1],d[50],r;

int main (void)
{
while (1)
{
int j=0;
printf ("%d",result);
printf ("please input a char and number\n");
while ((a=getchar())!='\n')
{
b[ j ]=a;
}

while((r=getchar())!='\n')
{
d[j]=r;
j++;
}
for(k=0;k<j;k++)
{
for(l=0;l<k;l++)
y*=10;
valuess+=((int)d[k]-48)*y;
}
y=1;j=0;
if ((b[0]=='q')||(b[0]=='Q'))
{
break;
}
switch (b[0])
{
case '+':
{
result += valuess;
break;
}
case '-':
{
result -= valuess;
break;
}
case '*':
{
result *= valuess;
break;
}
case '/':
{
if (valuess==0)
printf ("wrong ,please input a number\n");
else
result /= valuess;
break;
}
default:
{
printf ("unknow the operator%c","a\n");
break;
}
}
valuess=0;
}
return (0);
}