表达式计算（C++实现）

目前正在学习数据结构，根据书本上的思路自己捣鼓了一个表达式计算的小程序，目前支持负数、小数运算和报错。

下面贴上代码，代码写的很烂（耦合度比较高，比较繁琐），大家如果有什么更好的建议可以提一下！

PS：第一次写博客，诚惶诚恐

#include 
#include 
#include  //cin>>string
#include  //strcpy_s()
#include  //pow()
using namespace std;

char ops[] = { '+','-','/','*','(',')','#','.','0','1','2','3','4' ,'5','6','7','8','9' };//符号集
int icp[] = { 2,2,4,4,7,1,0,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1 };//进栈优先级
int isp[] = { 3,3,5,5,1,7,0,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1 };//栈内优先级

class Calculator {
public:
    Calculator();
    ~Calculator();
    void Run();
private:
    char* cOrin;//中缀表达式数组
    char** cResu;//后缀表达式
    void Initialize();//初始化
    bool ErrCheck(string expr);//检错
    int icpF(char c);//栈外优先级搜索
    int ispF(char c);//栈内优先级搜索
    void InToPost();//中缀转后缀
    double getOperand(int pos);//获取数字
    double doOperation(char Operator, double op1, double op2);//计算
};

Calculator::Calculator() {
    cOrin = NULL;
    cResu = NULL;
}

Calculator::~Calculator() {
    delete[] cOrin;
    int size = sizeof(*this->cResu) / sizeof(char*);
    for (int i = 0; i < size; i++) {
        delete[] this->cResu[i];
    }
    delete[] this->cResu;
}

void Calculator::Initialize() {
    string cinOrder = "";//中缀表达式
    int size = 0;//表达式长度
    while (true) {
        cout << "请输入表达式：";
        cin >> cinOrder;
        size = cinOrder.size();
        if (this->ErrCheck(cinOrder) == true) {
            goto loop;
        }
        else {
            break;
        }
    loop: {
        cinOrder = "";
        size=0;
        continue;
        }
    }
    this->cOrin = new char[size + 2];
    this->cResu = new char*[size + 1];
    strcpy_s(this->cOrin, size+1, cinOrder.c_str());
    this->cOrin[size] = '#';//标识表达式结束
    this->cOrin[size + 1] = '\0';//标识数组结束
}

bool Calculator::ErrCheck(string expr){
    int rBrace = 0;//右括号计数
    int lBrace = 0;//左括号计数
    bool isInvaild = false;//非法输入
    bool isDefalut = false;//括号不匹配
    for (int count = 0; count < expr.size(); count++) {
        if (expr[count] == '(') {
            lBrace++;
        }
        else if (expr[count] == ')') {
            rBrace++;
        }
        if (this->icpF(expr[count]) == -2) {
            isInvaild = true;
        }
    }
    if (lBrace != rBrace) {
        isDefalut = true;
    }
    if (isInvaild == true) {
        cout << "表达式含有非法字符，请检查！\n";
    }
    if (isDefalut == true) {
        cout << "表达式左右括号不匹配，请检查！\n";
    }
    if (isInvaild == true || isDefalut == true) {
        return true;
    }
    else {
        return false;
    }
}

void Calculator::Run() {
    int count = 0;
    int search;
    double op1, op2, number;
    this->Initialize();
    this->InToPost();
    stack<double> s;
    while (this->cResu[count][0] != '#') {
        search = this->icpF(this->cResu[count][0]);
        if (search == -1) {
            number = this->getOperand(count);
            s.push(number);
        }
        else {
            op2 = s.top();//后进先出
            s.pop();
            op1 = s.top();
            s.pop();
            number=this->doOperation(this->cResu[count][0], op1, op2);
            s.push(number);
        }
        count++;
    }
    number = s.top();
    s.pop();
    cout << "结果为：" << number << endl;
}

double Calculator::doOperation(char Operator, double op1, double op2) {
    double number = 0;
    switch (Operator) {
    case '+':
        number = op1 + op2;
        break;
    case '-':
        number = op1 - op2;
        break;
    case '*':
        number = op1*op2;
        break;
    case '/':
        number = op1 / op2;
        break;
    }
    return number;
}

double Calculator::getOperand(int pos) {
    double total = 0.0;//实际数字
    bool isDec = false;//判断是否小数
    int intCount = 0;//整数计数
    int count = 0;//数组遍历计数
    int numBit = 0;//每位上的数字
    int i = 0;//小数次方计数
    while (this->cResu[pos][count] != '+'
        && this->cResu[pos][count] != '-') {
        if (this->cResu[pos][count] == '.') {
            isDec = true;
            break;
        }
        else {
            intCount++;
            count++;
        }
    }
    while (this->cResu[pos][count] != '+'
        && this->cResu[pos][count] != '-') {//当遇到小数时，将计数移到符号位上
        count++;
    }
    if (this->cResu[pos][count] == '+') {//正数
        count = 0;
        if (isDec == true) {//是小数
            while (this->cResu[pos][count] != '.') {
                numBit = this->cResu[pos][count++] - '0';
                total += numBit*pow(10, --intCount);
            }
            count++;//跳过小数点
            while (this->cResu[pos][count] != '+') {
                numBit = this->cResu[pos][count++] - '0';
                total += numBit*pow(10, --i);
            }
        }
        else {//不是小数
            while (this->cResu[pos][count] != '+') {
                numBit = this->cResu[pos][count++] - '0';
                total += numBit*pow(10, --intCount);
            }
        }
    }
    else {//负数
        count = 0;
        if (isDec == true) {//是小数
            while (this->cResu[pos][count] != '.') {
                numBit = this->cResu[pos][count++] - '0';
                total += numBit*pow(10, --intCount);
            }
            count++;//跳过小数点
            while (this->cResu[pos][count] != '-') {
                numBit = this->cResu[pos][count++] - '0';
                total += numBit*pow(10, --i);
            }
            total = -total;
        }
        else {//不是小数
            while (this->cResu[pos][count] != '-') {
                numBit = this->cResu[pos][count++] - '0';
                total += numBit*pow(10, --intCount);
            }
            total = -total;
        }
    }
    return total;
}

int Calculator::icpF(char c) {
    int j = -2;
    for (int i = 0; i < 18; i++) {
        if (ops[i] == c) {
            j = icp[i];
        }
    }
    return j;
}

int Calculator::ispF(char c) {
    int j = -2;
    for (int i = 0; i < 18; i++) {
        if (ops[i] == c) {
            j = isp[i];
        }
    }
    return j;
}

void Calculator::InToPost() {
    bool isDec = false;//判断是否为小数
    bool isNeg = false;//判断是否为负数
    int cInCount = 0;//中缀表达式计数
    int cPostCount = 0;//后缀表达式计数
    int nCount = 0;//数字位数计数
    char c = '\0';
    int i;//优先级
    int temp;//重置中缀表达式计数
    stack<char> s;
    s.push('#');//确保扫描到的第一个运算符进栈
    while (true) {
        c = this->cOrin[cInCount];//扫描中缀表达式
        i = this->icpF(c);
        if (i == -1) {//没扫到运算符
            temp = cInCount;
            while ((i = this->icpF(this->cOrin[cInCount])) == -1) {//确定数字位数
                if (this->cOrin[cInCount] == '.') {//遇到小数点
                    isDec = true;
                    cInCount++;
                }
                else {
                    nCount++;
                    cInCount++;
                }
            }
            if (isNeg == false) {//如果不是负数
                if (isDec == true) {
                    this->cResu[cPostCount] = new char[nCount + 3];//存放小数点、正号和'\0'
                    for (int j = 0; j < nCount + 1; j++, temp++) {//输出数字
                        this->cResu[cPostCount][j] = this->cOrin[temp];
                    }
                    this->cResu[cPostCount][nCount + 1] = '+';
                    this->cResu[cPostCount][nCount + 2] = '\0';
                    isDec = false;//重置小数布尔值
                }
                else {
                    this->cResu[cPostCount] = new char[nCount + 2];//存放正号和'\0'
                    for (int j = 0; j < nCount; j++, temp++) {//输出数字
                        this->cResu[cPostCount][j] = this->cOrin[temp];
                    }
                    this->cResu[cPostCount][nCount] = '+';
                    this->cResu[cPostCount][nCount + 1] = '\0';
                }
            }
            else {//如果是负数
                if (isDec == true) {
                    this->cResu[cPostCount] = new char[nCount + 3];//存放小数点、负号和'\0'
                    for (int j = 0; j < nCount + 1; j++, temp++) {//输出数字
                        this->cResu[cPostCount][j] = this->cOrin[temp];
                    }
                    this->cResu[cPostCount][nCount + 1] = '-';
                    this->cResu[cPostCount][nCount + 2] = '\0';
                    cPostCount++;
                    isDec = false;//重置小数布尔值
                }
                else {
                    this->cResu[cPostCount] = new char[nCount + 2];//存放负号和'\0'
                    for (int j = 0; j < nCount; j++, temp++) {//输出数字
                        this->cResu[cPostCount][j] = this->cOrin[temp];
                    }
                    this->cResu[cPostCount][nCount] = '-';
                    this->cResu[cPostCount][nCount + 1] = '\0';
                }
                isNeg = false;//重置负数布尔值
            }
            cPostCount++;
            nCount = 0;
        }
        else {//扫描到运算符
            if (c == ')') {
                while (s.top() != '(') {//连续输出直到遇到'('
                    this->cResu[cPostCount] = new char[1];
                    this->cResu[cPostCount][0] = s.top();
                    s.pop();
                    cPostCount++;
                }
                s.pop();//'('直接出栈不输出
                cInCount++;
            }
            else if (this->cOrin[cInCount] == '-'
                && cInCount == 0) {//表达式例子：-4+5#
                isNeg = true;
                cInCount++;//跳过负号
                continue;
            }
            else if (this->cOrin[cInCount] == '-'
                && cInCount > 0
                && this->cOrin[cInCount - 1] != ')'
                && this->icpF(this->cOrin[cInCount - 1]) != -1) {//表达式例子：((-4+5)+1)*3#
                isNeg = true;
                cInCount++;//跳过负号
                continue;
            }
            else if (i <= ispF(s.top())) {//进栈优先级小于栈内优先级，一直输出
                while (i <= this->ispF(s.top())) {
                    this->cResu[cPostCount] = new char[1];
                    this->cResu[cPostCount][0] = s.top();
                    s.pop();
                    if (s.empty() == true) {
                        goto exit;//当遇到中缀表达式的#时，一直输出到栈空然后退出函数
                    }
                    cPostCount++;
                }
            }
            else {//进栈优先级大于栈内优先级，入栈
                s.push(c);
                cInCount++;
            }
        }
    }
exit:
    return;
}

int main() {
    Calculator c1;
    c1.Run();
    system("pause");
    return 0;
}