表示数值的字符串

class Solution {
public:
    bool isNumeric(char* string)
    {
        //e/E出现的位置
        int e = -1;
        //为了方便描述，下面所说e代表e/E
        //e前面加减号的个数
        int epreplus = 0;
        //e后面加减号的个数
        int ebehplus = 0;
        //e前面逗号的个数
        int epredot = 0;
        //e后面逗号的个数
        int ebehdot = 0;
        //e前面整数部分的值       //e前面小数部分的值
        double eprev1 = 0.0, eprev2 = 0.0;
        //e前面逗号的位置
        int epredotpos = -1;
        //e前面的值
        int ebehv = 0;
        for(int i = 0 ; string[i] != ‘\0‘ ; i++){

            if(string[i] == ‘E‘ || string[i] == ‘e‘){
                //出现两次e
                if(e != -1){
                //    cout<<"c1"<<endl;
                    return false;
                }
                e = i;
                //非法字符判断
            }else if(string[i] != ‘.‘ && string[i] != ‘+‘ && string[i] != ‘-‘
                     && (!(string[i]>=‘0‘ && string[i] <= ‘9‘))){

                  //      cout<<"c2"<<endl;
                         return false;
            }
            //逗号次数判断
            if(string[i] == ‘.‘){
                if(e == -1){
                    epredot ++;
                    //如果e前面逗号大于1个
                    if(epredot>1) {
                  //      cout<<"c3"<<endl;
                        return false;
                    }
                }else{
                    //e后面出现逗号
                //    cout<<"c4"<<endl;
                    return false;
                }
            }
            //加减号次数判断
            if(string[i] == ‘+‘ || string[i] == ‘-‘){
                if(e != -1){
                    epreplus++;
                    //e前面加减号出现次数大于1
                    if(epreplus>1){
                    //    cout<<"c5"<<endl;
                        return false;
                    }
                }else{
                    ebehplus++;
                    //e后面加减号出现次数大于1
                    if(ebehplus >1){
                   //   cout<<"c6"<<endl;
                      return false;
                    }
                }
            }
            if(string[i] != ‘e‘ && string[i] != ‘E‘){
                if(e == -1){
                    if(string[i] == ‘-‘ || string[i] == ‘+‘){
                        //e前面的逗号必须是第一个字符
                        if(i != 0){
                           // cout<<"c7"<<endl;
                          return false;
                        }
                    }
                    if(string[i] == ‘.‘){
                        epredotpos = i;
                    }else if(string[i] >= ‘0‘ && string[i] <= ‘9‘){
                        if(epredotpos == -1){
                            //e前面整数部分
                            eprev1 = eprev1 * 10 + string[i]-‘0‘;
                        }else{
                            //e前面小数部分
                            eprev2 = eprev2 + (string[i]-‘0‘)/pow(10, i-epredotpos);
                        }
                    }
                }else{
                    if(string[i] == ‘+‘ || string[i] == ‘-‘) {
                        //e后面正负号必须紧邻e
                        if(i-e != 1){
                         //   cout<<"c8"<<endl;
                            return false;
                        }
                    }
                    if(string[i] >= ‘0‘ && string[i] <= ‘9‘){
                       // cout<<"string[i]="<<string[i]<<endl;
                       //e后面的值
                        ebehv = ebehv*10 + string[i]-‘0‘;
                    }
                }
            }
        }

        double eprev = eprev1+eprev2;
        //cout<<"eprev="<< eprev<<endl;
        //存在e且e前面的值为0或小于1
        if(e != -1 && (eprev == 0 || eprev < 1)){
          //  cout<<"c10"<<endl;
            return false;
        }
        //存在e且e后面的值等于0
        if(e != -1 && ebehv == 0){
            //cout<<"c11"<<endl;
            return false;
        }
        return true;
    }
};