简单表达式求值

此表达式求值程序利用Stack实现




/**//******************************


Date:


2006 - 10 -24


Description:


This programe is aiming to


carry out operator counting by


using of sequence stack


*******************************/


#include "stdio.h"


#define MAXSIZE 128


typedef char DataType;


int pIFX = 0;


int pPFX = 0;


int pTP = 0;






/**//***Define a Stack Struct***/


typedef struct




...{


DataType stack[MAXSIZE];


}SeqStack;




/**//**********初始化PFX IFX************/




SeqStack PFX;


SeqStack IFX;


SeqStack TP;






/**//***************************


Function: Stack push


Param: SeqStack ss, char dat


Return: SeqStack


****************************/


SeqStack Push(SeqStack s, char dat)




...{


s.stack[pPFX] = dat;


return s;




}




/**//***************************


Function: Stack pop


Param: SeqStack ss, char dat


Return: SeqStack


****************************/


SeqStack Pop(SeqStack s, char dat)




...{




}


int CtoD(char c)




...{


return(c - '0');


}


char DtoC(int x)




...{


return(x + 48);


}




char InputPression(void)




...{


int i = 0;


char ch;


scanf("%c",&ch);


while(ch!= '=')




...{


IFX.stack[i ++] = ch;


scanf("%c",&ch);


}


IFX.stack[i] = '=';




}




void PrintStack(SeqStack s)




...{


int i = 0;


while(s.stack[i] != '=')


printf("%c",s.stack[i++]);


getchar();


getchar();


}


SeqStack toSufix()




...{


int pIFX = 0;


char ch;


TP.stack[pTP++] = '=';


while(IFX.stack[pIFX]!= '=')




...{


ch = IFX.stack[pIFX];


switch(ch)




...{


case '0':case '1':case '2':case '3':


case '4':case '5':case '6':case '7':


case '8': case'9':


PFX.stack[pPFX++] = ch;




break;


case '(':


TP.stack[++pTP] = '(';




break;


case ')':


while(TP.stack[pTP] != '(')




...{


PFX.stack[pPFX++] = TP.stack[pTP];


pTP--;


}


pTP--;




break;


case '+':


case '-':


while(


(pTP > 1 && TP.stack[pTP] != '(') &&


(TP.stack[pTP]== '+' || TP.stack[pTP]== '-')


)


PFX.stack[pPFX++] = TP.stack[pTP--];


pTP ++;


TP.stack[pTP]= ch;




break;


case '*':


case '/':


while(


pTP > 1 &&


(TP.stack[pTP]== '*' || TP.stack[pTP]== '/')


)


PFX.stack[pPFX++] = TP.stack[pTP--];


pTP++;


TP.stack[pTP] = ch;




break;




}/**//*end switch*/


pIFX++;




}/**//*end while*/


while(pTP > 1)


PFX.stack[pPFX++] = TP.stack[pTP--];


PFX.stack[pPFX] = '=';


}


int Computing()




...{


char ch;


char tmp1;


char tmp2;


int tmp;


pPFX = 0;


pIFX = 0;


pTP = 0;


while(PFX.stack[pPFX]!= '=')




...{


ch = PFX.stack[pPFX];


switch(ch)




...{


case '0':case '1':case '2':case '3':


case '4':case '5':case '6':case '7':


case '8': case'9':


pTP++;


TP.stack[pTP] = ch;


break;


case '+':


tmp1 = TP.stack[pTP--];


tmp2 = TP.stack[pTP--];


tmp = CtoD(tmp1) + CtoD(tmp2);


TP.stack[++pTP] = DtoC(tmp);


break;


case '-':


tmp1 = TP.stack[pTP--];


tmp2 = TP.stack[pTP--];


tmp = CtoD(tmp1) - CtoD(tmp2);


TP.stack[++pTP] = DtoC(tmp);


break;


case '*':


tmp1 = TP.stack[pTP--];


tmp2 = TP.stack[pTP--];


tmp = CtoD(tmp1) * CtoD(tmp2);


TP.stack[++pTP] = DtoC(tmp);


break;


case '/':


tmp1 = TP.stack[pTP--];


tmp2 = TP.stack[pTP--];


tmp = CtoD(tmp1) / CtoD(tmp2);


TP.stack[++pTP] = DtoC(tmp);


break;






}/**//*end switch*/


pPFX ++;




}/**//*end while*/


return(CtoD(TP.stack[1]));


}








/**//******************************


Main Function


*******************************/


int main()




...{


printf("Input count pression: ");


InputPression();


PrintStack(IFX);


PFX = toSufix();


PrintStack(PFX);


printf("%d",Computing());


getchar();


}





未完成...