f0512.cpp

it is a usefull thing

//=====================================
// f0512.cpp
// 命令解析
//=====================================
#include<iostream>
#include<sstream>
using namespace std;
//-------------------------------------
int main(int argc, char** argv){
  if(argc!=2){
    cout<<"usage: f0512 command\n";
    return 1;
  }
  string s(argv[1]);
  istringstream sin(s);
  int a,b;  char c;
  sin>>a>>c>>b;
  switch(c){
    case'-': b=-b;
    case'+': cout<<a+b; break;
    case'*': cout<<a*b; break;
    case'/': cout<<a/b; break;
    default: cout<<"error";
  }
}//====================================