#include "Calculator.h"
Calculator::Calculator(){
}
void Calculator::processInput(){
char c;
while((c=getchar()) != '#'){
charQueue.push(c);
}
/*
while(!charQueue.empty()){
cout<<charQueue.front()<<" ";
charQueue.pop();
}
cout<<endl;
*/
}
bool Calculator::isPriority(char optr1,char optr2){//optr1 is the icp,and the optr2 is the isp
if(optr1 == '^'){
if(optr2 == '^')
return false;
else
return true;
}
else if(optr1 == '*' || optr1 == '/' || optr1 == '%'){
if(optr2 == '^' || optr2 == '*' || optr2 == '%' ||optr2 == '*')
return false;
else
return true;
}
else if(optr1 == '+' || optr1 == '-'){
return false;
}
return false;
}
int Calculator::getResult(int num1,int num2,char optr){
int result = 0;
switch(optr){
case '^':
result = 1;
for(int i=0;i<num1;i++)
result *= num2;
break;
case '*':
result = num1*num2;
break;
case '/':
result = num2/num1;
break;
case '%':
result = num2%num1;
break;
case '+':
result = num1+num2;
break;
case '-':
result = num2-num1;
break;
default:
break;
}
return result;
}
void Calculator::process(){
char c;
while(!charQueue.empty()){
c = charQueue.front();//get the front element
charQueue.pop();
if(isdigit(c)){//the char c is a digit
int temNum = c-'0';
while(!charQueue.empty() && isdigit(charQueue.front())){
c = charQueue.front();
charQueue.pop();
temNum = (temNum*10) + (c-'0');//calculate the current result
}
//push the num to the numStack
numStack.push(temNum);
}else{//it must be a optr
if(c != '^' && c != '%' && c != '/' && c != '*' && c != '+' && c != '-'){
cout<<"invalide input!please check!"<<endl;
return;
}
else{
if(optrStack.empty()){//the optrStack is empty
optrStack.push(c);
}
else{//the optrStack is unempty
if(isPriority(c,optrStack.top())){//icp>isp,push the icp
optrStack.push(c);
}else{//icp<=isp,pop one from optrStack,pop two from numStack,getResult,push the
//result to the numStack,push the icp to optrStack
char temOptr = optrStack.top();
optrStack.pop();
int temNum1 = numStack.top();
numStack.pop();
int temNum2 = numStack.top();
numStack.pop();
//get the result
int temResult = getResult(temNum1,temNum2,temOptr);
//push the result
numStack.push(temResult);
//push the c
optrStack.push(c);
}
}
}
}
}
//finish the input,then get the final result
while(!optrStack.empty()){//while the optrStack is unEmpty
char temOptr = optrStack.top();
optrStack.pop();
int temNum1 = numStack.top();
numStack.pop();
int temNum2 = numStack.top();
numStack.pop();
//get the result
int temResult = getResult(temNum1,temNum2,temOptr);
numStack.push(temResult);
}
int finalResult = 0;
if(!numStack.empty()){
finalResult = numStack.top();
numStack.pop();
}
//check the numStack
if(!numStack.empty()){
cout<<"There is an error in the expression,please check!";
return;
}else{
cout<<"The final result of the input expression is: "<<finalResult<<endl;
return;
}
}
void Calculator::clean(){
while(!optrStack.empty()){
optrStack.pop();
}
while(!numStack.empty())
numStack.pop();
while(!charQueue.empty())
charQueue.pop();
}
void Calculator::calculate(){
processInput();
process();
clean();
}
