C++中输入三个字符串，第三个老是无法写入，怎么回事？在线等
int main(){ char *p1=new char[MAX_LEN]; cout<<"请输入字符串S1："; cin.getline(p1,MAX_LEN-1); String s1(p1); char *p2=new char[MAX_LEN]; cout<<"请输入待查找子串S2："; cin.getline(p2,MAX_LEN-1); String s2(p2); cout<<"验证bool is_substring(const char* p)\n"; if(s1.is_substring(p2)) cout<<"S1中找到S2！"<<endl; else cout<<"S1未找到S2！"<<endl; cout<<"验证bool is_substring(const String &p)\n"; if(s1.is_substring(s2)) cout<<"S1中找到S2！\n"<<endl; else cout<<"S1未找到S2！\n"<<endl; cout<<"验证String substring(int start,int length)\n"; int start,length; cout<<"请输两个整数（起始位置、子串长度）："; cin>>start>>length; if(s1.substring(start,length).get_str()!=NULL) { cout<<"在S1中搜寻结果为："<<s1.substring(start,length).get_str()<<endl; } else ; cout<<"\n验证int find_replace_str(const char* find_str,const char* replace_str)\n\n"; char *p3=new char[MAX_LEN]; cout<<"请输入用于替换子串的字符串S3："<<endl; cin.getline(p2,MAX_LEN-1); String s3(p3); cout<<"\n在S1中找到S2的次数为"<<s1.find_replace_str(p2,p3)<<endl; cout<<"替换后的S1为："<<s1.get_str()<<endl;