C++四则计算器源码 - c++编程基础

我建议每个像我一样的小白，都自己动手写一下，四则计算器，因为这里面既有队列的知识，又有栈的知识，又有字符串处理的知识，而且还可以对自己的逻辑思维进行一定强度的锻炼，可以说有百利而无一害！我这里写的代码仅供大家参考，因为比较简单我也没怎么写注释。talking is cheapshow me the code

#include   
#include   
#include   
using namespace std;  
const int INF=1000;  
  
//调度场算法 中缀表达式转后缀表达式  
template  queue& dispatch(pair infix[],long size){  
    //var can't use to convert type,but we can use it to define a type;  
    stack> operators;  
    queue* result=new queue;  
    for (int i=0; ipush(infix[i].first);  
        }else if(infix[i].second!=INF){//or it is a operator;  
            if(operators.empty()){  
               operators.push(infix[i]);  
            }else if(infix[i].second>operators.top().second){  
                operators.push(infix[i]);  
            }else{  
                do{  
                    result->push(operators.top().first);  
                    operators.pop();  
                } while (!operators.empty()&&infix[i].second<=operators.top().second);  
                  
                operators.push(infix[i]);  
              
            }  
          
        }  
          
    }  
    while(!operators.empty()){  
        result->push(operators.top().first);  
        operators.pop();  
    }  
     
    return *result;  
}  
//创建带有优先级的操作符pair  
pair* init_infix_pair(vector infix,long size) {  
    pair* opers=new pair[size];  
    int current_priority=1;  
    for (int i=0; i oper(infix[i],0);  
        if(infix[i]=="("){current_priority+=2;oper.second=INF;}  
        else if(infix[i]==")"){current_priority-=2;oper.second=INF;}  
        else if(infix[i]=="*"||infix[i]=="/"){  
            oper.second=current_priority+1;  
        }else if(infix[i]=="+"||infix[i]=="-"){  
            oper.second=current_priority;  
        }  
        opers[i]=oper;  
    }  
    return opers;  
}  
//把字符串转换成字符串数组,以运算符作为分隔符,可以处理小数点  
vector&  convert_string_to_array(string exp){  
    int start,end;  
    vector* vec=new vector;  
    for (int i=0; i='0'&&exp[i]<='9'){  
            if(!isdigit(exp[i-1])&&exp[i-1]!='.'){  
                start=i;  
            }  
        }else{  
            if(exp[i]=='.')continue;  
            if(i==0||!isdigit(exp[i-1])){  
               vec->




push_back(exp.substr(i,1));  
            }  
            else{  
                end=i;  
                vec->push_back(exp.substr(start,end-start));  
                vec->push_back(exp.substr(i,1));  
            }  
              
        }  
    }  
    return *vec;  
}  
//构建一个vector,元素为pair,first标识是数字还是运算符,second为具体内容  
vector< pair >& convert_queue_to_vector(queue result){  
    vector>* vec=new vector>;  
    while(!result.empty()){  
         
        char oper=*result.front().c_str();  
        if(oper=='+'||oper=='-'||oper=='*'||oper=='/'){  
            vec->push_back(pair(true,oper));  
            result.pop();  
            continue;  
        }  
        vec->push_back(pair(false,atof(result.front().c_str())));  
        result.pop();  
    }  
    return *vec;  
}  
//利用栈计算后缀表达式  
double caculate_string_vector(vector> vec){  
    stack result_stack;  
    for (int i=0; i& vec=convert_string_to_array(exp);  
    vector::iterator it=vec.begin();  
    while (it!=vec.end()) {  
        cout<<*it<<" ";  
        it++;  
    }  
    cout<* ps=init_infix_pair(vec,vec.size());  
    queue& result=dispatch(ps,vec.size());  
      
    vector< pair >& final=convert_queue_to_vector(result);  
    cout<< caculate_string_vector(final)<