C语言数据结构之简易计算器

本文实例为大家分享了C语言简易计算器的具体代码，供大家参考，具体内容如下

主要解决了处理负数、小数等的基础运算操作，无图形界面

#include <iostream>
#include <stack>
using namespace std;

class Calculator{
private:
 int Priority(char fuhao);
 double CalSuffix(string PostfixExp);

public:
 double Calculate(string InfixExp);

  string InfixToSuffix(string InfixExp);

};

double Calculator::CalSuffix(string PostfixExp){
 double tmpresult,ch1,ch2;
 double tmpnum,tmpxiaoshu=1;
 int i=0,tmpdashu;
 int isfu=0; ///
 stack<double> stk2;
 while(PostfixExp[i]!='\0'){
  isfu=0; ///
  if(PostfixExp[i]>=48&&PostfixExp[i]<=57){
   if(PostfixExp[i-1]=='-'){  /////
    isfu=1;
   }
   tmpxiaoshu=1;
   tmpdashu=10;
   tmpnum = PostfixExp[i]-48;
   while(PostfixExp[++i]>=48&&PostfixExp[i]<=57){
    tmpnum = tmpnum*tmpdashu+ (PostfixExp[i]-48);
   }
   i=i-1;
   if(PostfixExp[++i]=='.'){
    while(PostfixExp[++i]>=48&&PostfixExp[i]<=57){
     tmpxiaoshu=tmpxiaoshu*0.1;
     tmpnum = tmpnum + (PostfixExp[i]-48)*tmpxiaoshu;
    }
    i=i-1;
   }
   else{
    i=i-1;
   }
   if(isfu){ ////
    tmpnum=tmpnum*(-1);
   }
   stk2.push(tmpnum);
  }

  else if(PostfixExp[i]=='&'||PostfixExp[i]==' '){
  }

  else {
   if(PostfixExp[++i]>=48&&PostfixExp[i]<=57){
    i=i-1;
   }
   else {
    i=i-1;
    ch2 = stk2.top();
    stk2.pop();
    ch1 = stk2.top();
    stk2.pop();
    switch(PostfixExp[i]){
     case '+': tmpnum = ch1 + ch2; break;
     case '-': tmpnum = ch1 - ch2; break;
     case '*': tmpnum = ch1 * ch2; break;
     case '/': tmpnum = ch1 / ch2;
      if(ch2==0) cout<<"除数为零";break;
    }
    stk2.push(tmpnum);
   }
  }
  i++;
 }
 if(stk2.empty()!=1){
  tmpresult = stk2.top();
  stk2.pop();
 }
 return tmpresult;
}

double Calculator::Calculate(string InfixExp){
 double result;
 result = CalSuffix(InfixToSuffix(InfixExp));
 return result;
}

int Calculator::Priority(char fuhao){
 switch(fuhao){
  case '+':
  case '-': return 2;
  case '*':
  case '/': return 3;
  case '(':
  case ')': return 1;
  default:
   return 0;
 }
}
string Calculator::InfixToSuffix(string InfixExp){
 stack<char> stk;
 string PostfixExp = "     ";
 int i=0,j=0;
 char tmpfuhao;
 int flag = 0; //判断多位数的头数是否为零
 while(InfixExp[i]!='\0'){
  if(InfixExp[i]>=48&&InfixExp[i]<=57){
   flag = 0;
   PostfixExp[j++]='&';
   PostfixExp[j++]=InfixExp[i];
   if(InfixExp[i]=='0'){
    flag = 1;
   }
   while(InfixExp[++i]>=48&&InfixExp[i]<=57){
    if(flag==0)
     PostfixExp[j++]=InfixExp[i];
    else
     cout<<"输入错误数字";
   }
   i=i-1;
   if(InfixExp[++i]=='.'){
    PostfixExp[j++]='.';
    while(InfixExp[++i]>=48&&InfixExp[i]<=57){
     PostfixExp[j++]=InfixExp[i];
    }
    i=i-1;
   }
   else{
    i=i-1;
   }
  }

  else if(InfixExp[i]=='('){
   stk.push(InfixExp[i]);
  }

  else if(InfixExp[i]==')'){
   if(stk.empty()){
    cout<<"表达式错误！";
   }
   else{
    tmpfuhao = stk.top();
    while(tmpfuhao!='('){
     if(stk.empty()){
      cout<<"表达式错误!";
     }
     else{
      PostfixExp[j++] = '&';
      PostfixExp[j++] = tmpfuhao;
      stk.pop();
      tmpfuhao = stk.top();
     }
    }
    stk.pop();
   }
  }

  else if(InfixExp[i]=='+'||InfixExp[i]=='-'||InfixExp[i]=='*'||InfixExp[i]=='/'){
   if(i==0||((InfixExp[--i]<48||InfixExp[i]>57)&&InfixExp[i]!=')')){
    i++;
    PostfixExp[j++]='&';
    PostfixExp[j++]='-';
    while(InfixExp[++i]>=48&&InfixExp[i]<=57){
     PostfixExp[j++]=InfixExp[i];
    }
    i=i-1;
    if(InfixExp[++i]=='.'){
     PostfixExp[j++]='.';
     while(InfixExp[++i]>=48&&InfixExp[i]<=57){
      PostfixExp[j++]=InfixExp[i];
     }
     i=i-1;
    }
    else{
     i=i-1;
    }
   }
   else{
    i++;
   if(stk.empty()){
    stk.push(InfixExp[i]);
   }
   else{
    tmpfuhao = stk.top();
    if(Priority(tmpfuhao)<Priority(InfixExp[i])){
     stk.push(InfixExp[i]);
    }
    else{
     while(Priority(tmpfuhao)>=Priority(InfixExp[i])){
      PostfixExp[j++] = '&';
      PostfixExp[j++] = tmpfuhao;
      stk.pop();
      if(stk.empty()!=1){
       tmpfuhao = stk.top();
      }
      else break;
     }
     stk.push(InfixExp[i]);
    }
   }
   }
  }
  else{
   cout<<"符号错误！";
   break;
  }
  i++;
 }

 while(!stk.empty()){
  tmpfuhao = stk.top();
  PostfixExp[j++] = '&';
  PostfixExp[j++] = tmpfuhao;
  stk.pop();
 }
 PostfixExp[j++] = '\0';
 return PostfixExp;
}

int main(int argc, const char * argv[]) {
 string a;
 Calculator a1;
 cin>>a;
 cout<<a1.Calculate(a)<<endl;
 cout<<a1.InfixToSuffix(a);
 return 0;
}

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