C/C++ 中缀表达式转换成后缀表达式并求值

来源：互联网发布：数据分析师专业编辑：程序博客网时间：2024/05/17 03:00
#include <stdio.h> #include <math.h> #include <stdlib.h> #define STACK_INIT_SIZE 100 #define STACKINCREMENT 10 typedef struct{     char *base;     char *top;     int stacksize; }SqStack1; typedef struct{     double *base;     double *top;     int stacksize; }SqStack2; SqStack1 OPTR; SqStack2 OPND; double EvaluateExpression(); void CHAR_InitStack(SqStack1 &S); void DOUBLE_InitStack(SqStack2 &S); char CHAR_GetTop(SqStack1 S); double DOUBLE_GetTop(SqStack2 S); int CHAR_Push(SqStack1 &S , char e); int DOUBLE_Push(SqStack2 &S , double e); char CHAR_Pop(SqStack1 &S , char &e); double DOUBLE_Pop(SqStack2 &S , double &e); char Precede(char a,char b); double Operate ( double d ,char e,double f); int In(char c); int main(void) {     double result;     printf("*************************\n");     printf("*      表达式计算       *\n");     printf("*************************\n");     printf("请输入一组表达式(以#号结束):\n");     result = EvaluateExpression();     printf("\n\n计算结果是(结果保留两位小数):%.2f\n\n\n",result); } void CHAR_InitStack(SqStack1 &S) {     S.base=(char *)malloc(STACK_INIT_SIZE * sizeof(char));     if(!S.base)exit(OVERFLOW);     S.top = S.base;     S.stacksize = STACK_INIT_SIZE; } void DOUBLE_InitStack(SqStack2 &S) {     S.base=(double *)malloc(STACK_INIT_SIZE * sizeof(double));     if(!S.base)exit(OVERFLOW);     S.top = S.base;     S.stacksize = STACK_INIT_SIZE; } char CHAR_GetTop(SqStack1 S) {     char e;     if(S.top == S.base) return -1;     e = *(S.top-1);     return e; } double DOUBLE_GetTop(SqStack2 S) {     double e;     if(S.top == S.base) return -1;     e = *(S.top-1);     return e; } int CHAR_Push(SqStack1 &S , char e) {     if(S.top - S.base >= S.stacksize)     {         S.base = (char *)realloc(S.base , (S.stacksize + STACKINCREMENT) * sizeof(char));         if(!S.base) exit(OVERFLOW);         S.top = S.base + S.stacksize;         S.stacksize += STACKINCREMENT;     }     *S.top++ = e;     return 1; } int DOUBLE_Push(SqStack2 &S , double e) {     if(S.top - S.base >= S.stacksize)     {         S.base = (double *)realloc(S.base , (S.stacksize + STACKINCREMENT) * sizeof(double));         if(!S.base) exit(OVERFLOW);         S.top = S.base + S.stacksize;         S.stacksize += STACKINCREMENT;     }     *S.top++ = e;     return 1; } char CHAR_Pop(SqStack1 &S , char &e) {     if(S.top == S.base)return -1;     e = * --S.top;     return e; } double DOUBLE_Pop(SqStack2 &S , double &e) {     if(S.top == S.base)return -1;     e = * --S.top;     return e; } int In(char c)  // 判断是否为运算符 {     if ( c=='(' || c=='+' || c=='-' || c == '*' || c=='/' || c==')' || c=='#' || c=='^')         return 1;     else         return 0; } char Precede(char a,char b) //判断优先级 {     char op;     switch(a)     {         case '#':             if (b=='#')                  op='=';             else op='<';             break;         case '+':             if (b=='*' || b=='/' || b=='('|| b=='^')                  op='<';             else op='>';             break;         case '-':             if (b=='*' || b=='/' || b=='(' || b=='^')                 op='<';             else op='>';             break;         case '*':             if (b=='(' || b=='^')                 op='<';             else op='>';             break;         case '/':             if (b=='(' || b=='^')                 op='<';             else op='>';             break;         case'^':             if(b=='(')                 op='<';             else op='>';             break;         case '(':             if (b==')')                 op='=';             else op='<';             break;         case ')':             op='>';             break;     }     return op; } double Operate( double d ,char e,double f) //计算 {     double g;     switch(e)     {         case '+':             g=d+f;             break;         case '-':             g=d-f;             break;         case '*':             g=d*f;             break;         case '/':             g=d/f;             break;         case '^':             g=pow(d,f);             break;     }     return g; } double EvaluateExpression() {     char c=0,theta,x;     double a,b,number, n=0;     CHAR_InitStack (OPTR);     CHAR_Push (OPTR,'#');     DOUBLE_InitStack (OPND);     c = getchar();     printf("\n转化成后缀表达式是:");     while (c!='#'|| CHAR_GetTop(OPTR)!='#')     {         if(!In(c))         {             number=0;             while(!In(c))             {                 if(c=='.')                     break;                 number = number*10 +(c-48);                 c = getchar();             }             if(c=='.')             {                 n=1;                 while(!In(c = getchar()))                 {                     number = number +(c-48)*(double)pow(0.1 , n);                     n++;                 }             }             DOUBLE_Push (OPND,number);                 printf("%.2f ",number);         }         else         switch (Precede(CHAR_GetTop(OPTR),c))         {             case '<':                 CHAR_Push(OPTR , c);                 c=getchar();                 break;             case '=':                 CHAR_Pop(OPTR , x);                 c=getchar();                 break;             case '>':                 CHAR_Pop(OPTR , theta);                 printf("%c ",theta);                 DOUBLE_Pop(OPND , a);                 DOUBLE_Pop(OPND , b);                 DOUBLE_Push(OPND,Operate(b,theta,a));                 break;         }     }     return (DOUBLE_GetTop(OPND)); }//int EvaluateExpression
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