四则混合运算的算法

#include "arithmetic.h" #include <iostream> #include "global.h" using namespace std; //-----------------------------input the infix expression----------------------------- void Api_arithmetic::getInfix() { char ch; cin.get(ch); int i=0; while(ch!='\n') { infix[i]=ch; cin.get(ch); i++; } ptr_infix=i; } //-------------------------------------constructor--------------- Api_arithmetic::Api_arithmetic() { infix=new char[MAX_SIZE]; postfix=new char[MAX_SIZE]; ptr_infix=0; ptr_postfix=0; } //-----------------------------------implement the function of the setColor----------------------- /*void Api_arithmetic::setColor(WORD Color) { SetConsoleTextAttribute(hOut,Color); } //----------------------------------implement the function of resetColor------------------------- void Api_arithmetic::colorReset() { SetConsoleTextAttribute(hOut,OriginalColor); }*/ //--------------------------------show the infix expression with color green---------------------- void Api_arithmetic::showInfix() { int i; setColor(GREEN); for(i=0;i<ptr_infix;i++) cout<<infix[i]; cout<<endl; colorReset(); } void Api_arithmetic::showPostfix() { int i; setColor(RED); convert2Postfix(); for(i=0;i<ptr_postfix;i++) cout<<postfix[i]; cout<<endl; colorReset(); } //------------------------------convert---------------------------------------------------------------------------- //convert infix expression into postfix //----------------------------------------------------------------------------------------------------------------- void Api_arithmetic::convert2Postfix() { char temp;//src char dst;//dst int priority;//to get the value of the function of precedence int ptr_temp=0; for(ptr_temp=0;ptr_temp<ptr_infix;ptr_temp++) { temp=infix[ptr_temp]; //<<temp<<endl; if(temp>='0'&&temp<='9') { postfix[ptr_postfix]=temp; ptr_postfix++; }//end if else if(temp=='+'||temp=='-'||temp=='*'||temp=='/')//compare the priority { if(!operators.isEmpty()) { dst=operators.getLastItem();//get the top element of the stack while(dst!='('&&!operators.isEmpty())//out loop while meet charcter '(' and pop out the character whose priority higher than src { priority=precedence(temp,dst); if(priority<=0) { operators.pop(postfix[ptr_postfix]); //cout<<"^"<<postfix[ptr_postfix]; ptr_postfix++; if(!operators.isEmpty()) dst=operators.getLastItem(); }//end if else break;//end else }//end while }//end if operators.push(temp); }//end else if else if(temp=='(') { operators.push(temp); }//end else if else if(temp==')') { operators.pop(dst); while(dst!='(') { postfix[ptr_postfix]=dst; ptr_postfix++; operators.pop(dst); }//end while }//end else if else if(temp=='=') { while(!operators.isEmpty()) { operators.pop(postfix[ptr_postfix]); //cout<<"!"<<postfix[ptr_postfix]; ptr_postfix++; }//end while }//end else if else { cout<<"input error"<<endl; }//end else }//end for } ///////////////////////////////////////////////////////////////////////////////////////////////// //This function is to compare the priority of the operators; //if the priority of the src higher than dst, return 1; if equal,return 0; else return -1; //////////////////////////////////////////////////////////////////////////////////////////////// int Api_arithmetic::precedence(char src,char dst) { if(src=='*'||src=='/') { if(dst=='+'||dst=='-') return 1; else return 0; }//end if else { if(dst=='+'||dst=='-') return 0; else return -1; } } Api_arithmetic::~Api_arithmetic() { delete[] infix; delete[] postfix; } /*void Api_arithmetic::precedence(char src,char dst,int& pri) { if(src=='*'||src=='/') { if(dst=='+'||dst=='-') pri=1; else pri=0; }//end if else { if(dst=='+'||dst=='-') pri=0; else pri=-1; } }*/