顺序栈各种基本运算算法的实现

#include "calculator.h" #include <iostream> using namespace std; //construction Calculator::Calculator(){ command=' '; } //get_command void Calculator::get_command(){ bool waiting =true; cout<<"Select command and press <Enter>:"; while(waiting){ cin>>command; command=tolower(command); if(command=='?'||command=='='||command=='+'|| command=='-'||command=='*'||command=='/'|| command=='q'||command=='c') waiting=false; else cout<<"Please enter a valid command:"<<endl <<"[?]push to stack [=]print top "<<endl <<"[+][-][*][/] are arithmetic operations"<<endl <<"[c]clean the stack"<<endl <<"[Q] quit"<<endl; } } //do_command bool Calculator::do_command(){ get_command(); switch(command){ case '?': PutInNum(); break; case '+': Add(); break; case '-': Sub(); break; case '*': Mul(); break; case '/': Div(); break; case 'c': Clear(); break; case '=': ShowResult(); break; case 'q': return false; } return true; } //Once enter '?': put the next number into stack void Calculator::PutInNum(){ Stack_entry p; cout<<"Enter a real number: "<<flush; cin>>p; if(numbers.push(p)==overflow) cout<<"Warning:Stack full,lost number"<<endl; } //Once enter '+' : Add the numbers in the stack void Calculator::Add(){ Stack_entry p,q; if(numbers.top(p)==underflow) cout<<"Stack empty"<<endl; else{ numbers.top(p); numbers.pop(); if(numbers.top(q)==underflow){ cout<<"Stack has just one entry"<<endl; numbers.push(p); } else{ numbers.pop(); if(numbers.push(p+q)==overflow) cout<<"Warning:Stack full,lost result"<<endl; else numbers.push(p+q); } } } //Once enter '-': Subtract the numbers in the stack void Calculator::Sub(){ Stack_entry p,q; if(numbers.top(p)==underflow) cout<<"Stack empty"<<endl; else{ numbers.top(p); numbers.pop(); if(numbers.top(q)==underflow){ cout<<"Stack has just one entry"<<endl; numbers.push(p); } else{ numbers.pop(); if(numbers.push(q-p)==overflow) cout<<"Warning:Stack full,lost result"<<endl; else numbers.push(q-p); } } } //Once enter'*': Multiply the numbers in the stack void Calculator::Mul(){ Stack_entry p,q; if(numbers.top(p)==underflow) cout<<"Stack empty"<<endl; else{ numbers.top(p); numbers.pop(); if(numbers.top(q)==underflow){ cout<<"Stack has just one entry"<<endl; numbers.push(p); } else{ numbers.pop(); if(numbers.push(p*q)==overflow) cout<<"Warning:Stack full,lost result"<<endl; else numbers.push(p*q); } } } //Once enter '/': Divide the numbers in the stack void Calculator::Div(){ Stack_entry p,q; if(numbers.top(p)==underflow) cout<<"Stack empty"<<endl; else{ numbers.top(p); numbers.pop(); if(p==0){ cout<<"Bed command! The second number is 0 and cannot finishi divide command!"<<endl; } else if(numbers.top(q)==underflow){ cout<<"Stack has just one entry"<<endl; numbers.push(p); } else{ numbers.pop(); if(numbers.push(q/p)==overflow) cout<<"Warning:Stack full,lost result"<<endl; else numbers.push(q/p); } } } //Once enter '=':Show the result of least command void Calculator::ShowResult(){ Stack_entry p; if(numbers.top(p)==underflow) cout<<"Stack empty"<<endl; else cout<<p<<endl; } //Once enter 'q':Stop the calculation void Calculator::Quit(){ cout<<"Calculation finished!"<<endl; } //Once enter 'c':Clear the stack void Calculator::Clear(){ numbers.clear(); }