在条件 C++ 语句中创建对象

#include #include <字符串>#include "report.h"使用命名空间标准；bool enter_company_name();//如果用户想输入公司名称，则返回真bool print_form();//如果用户想在格式化输出中打印，则返回 trueint main(){字符串公司名称，报告名称；布尔名称 = 假，格式=假；name = enter_company_name();格式 = print_form();如果(姓名){cout<<"输入公司名称:";getline(cin, company_name);cout<<"输入报告名称:";getline(cin，report_name)；报告标题(公司名称，报告名称)；//这是我的问题}别的报告标题；//这是我的问题如果(格式)header.print_formatted();别的header.print_one_line();返回0；}bool enter_company_name(){字符选择；cout<<"你想输入一个名字吗?
>";cin >>选择;如果(选择 == 'y' || 选择 == 'Y')返回真；别的返回假；}bool print_form(){字符选择；cout<<"你想打印一个格式化的标题吗?
>";cin >>选择;如果(选择 == 'y' || 选择 == 'Y')返回真；别的返回假；}

>

报告头；如果 (...) {标题 = 报告()；别的标题 = 报告(姓名，公司)；

或者用更短的方式:

报告头；//调用默认构造函数如果(shouldInitializeWithParams){标题 = 报告(姓名，公司)；}

当然，这需要您定义空构造函数.

I am learning c++, and I just got to the object oriented chapter. I have a question about creating objects inside if statements.

The problem I'm working on says to create a class that will display a report header. The class has a default constructor that sets the company name and report name to a generic thing, and also, if the user wants, has a constructor that takes two arguments (strings company name and report name).

The problem says, specifically, "A two-parameter default constructor should allow these [company and report names] to be specified at the time a new Report object is created. If the user creates a Report object without passing any arguments, use the default values. Otherwise, use user specified values for the names."

So my question is, how to create these objects? I understand how to create an object without any arguments (i.e. Report newobj;), and also with arguments (i.e. Report newobj(string string);). Basically, I get how to create these objects initially at the top of my main function. But is it possible to create them inside if statements based on user choices? Here is what I have so far and, obviously, it doesn't work:

#include <iostream>
#include <string>
#include "report.h"
using namespace std;

bool enter_company_name();           // return true if user wants to enter company name
bool print_form();              // return true if user wants to print in formatted output

int main()
{
  string company_name,
    report_name;
  bool name = false,
    format = false;

  name = enter_company_name();
  format = print_form();

  if (name)
    {
      cout << "Enter company name: ";
      getline(cin, company_name);
      cout << "Enter report name: ";
      getline(cin, report_name);
      Report header(company_name, report_name);  // THIS IS MY PROBLEM
    }
  else
      Report header;  // THIS IS MY PROBLEM

  if (format)
    header.print_formatted();
  else
    header.print_one_line();

  return 0;
}

bool enter_company_name()
{
  char choice;

  cout << "Do you want to enter a name?
>";
  cin >> choice;

  if (choice == 'y' || choice == 'Y')
    return true;
  else
    return false;
}

bool print_form()
{
  char choice;

  cout << "Do you want to print a formatted header?
>";
  cin >> choice;

  if (choice == 'y' || choice == 'Y')
    return true;
  else
    return false;
}

So I want to create an object using default values if none are specified, or create one with the user values if that's the choice given. I just can't figure out how to do it interactively in c++. I have not been able to find any similar questions anywhere so far.

The closest thing I've come across uses pointers to do something similar to what I want to do, but the book I'm using has not gotten to pointers yet, and I want to try to figure out a way to do it that stays within the bounds of the chapter I'm working in (i.e. not using pointers).

I didn't include the header file or class implementation file because I don't think they are relevant here.

Thank you in advance!

I don't know if I understood your question correctly but can't you just declare report before the if/else block and then initialize inside it?

Report header;

if (...) {
  header = Report();
else
  header = Report(name,company);

Or in a shorter way:

Report header; // calls default constructor

if (shouldInitializeWithParams) {
  header = Report(name,company);
}

Of course this requires you to have the empty constructor defined.

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