set method is not necessary if constructor parameters are given

14y1.7kVisual Basic .NET

Following one is an incomplete program of number 7 in Chapter4. The program is asking to include a constructor then talking about set method. It is confusing because in my view set method is not necessary if constructor parameters are given. Please complete this program.

using System;

namespace _4e7
{
class MovingHistory
{
static void Main(string[] args)
{
City myCity = new City("Scarborough","Ontario", 100000);
City myFriendCity = new City("British_Columbia", "Victoria", 700000);

}
}
}
class City
{
string cityName;
string cityState;
int population;

public City(string cityName, string cityState, int population)
{
this.cityName = cityName;
this.cityState = cityState;
this.population = population;
}
public string getCityName()
{
return cityName;
}
public string getCityState()
{
return cityState;
}
public int getPopulation()
{
return population;
}

}

9 Replies

Know the answer? Post it — somebody with the same question will find it here.

14y ago
Thank you
Vulpes14y ago
Although they're similar, they're not the same.

When you use {0, -15} the field will be filled with spaces until it's 15 characters wide and then the rest of the string will start from the next character after that.

With {0} the rest of the string will start from the next character after whatever's in the {0} is printed.
14y ago
{0, -15} is similar to {0} because both are aligned with the console edge but {0, -15} has effect on State & Population alignment. Could you explain this variation please.
Vulpes14y ago
Yes, something like {0, -15} in Console.WriteLine or String.Format means that whatever is to be placed in {0} should be left justified within a field which is 15 characters wide.

{0, 15} means that it should be right justified within a 15 character field.
14y ago
Thank you very much for your help.

Is it possible to explain the relation between left alignment and minus sing.
Vulpes14y ago
Sure, try this:

using System;

namespace _4e7
{
class MovingHistory
{
static void Main(string[] args)
{
Console.WriteLine("{0, -15} {1, -20} {2, -10}", "Name", "State", "Population");
Console.WriteLine("{0, -15} {1, -20} {2, -10}", "----", "-----", "----------");
City myCity = new City("Scarborough","Ontario", 100000);
City myFriendCity = new City("Victoria", "British_Columbia",700000);
DisplayCity(myCity);
DisplayCity(myFriendCity);
myCity.setCityName("Kingston"); // say
myCity.setPopulation(120000);
myFriendCity.setCityName("Vancouver"); // say
myFriendCity.setPopulation(600000);
DisplayCity(myCity);
DisplayCity(myFriendCity);
Console.ReadKey();
}

static void DisplayCity(City city)
{
Console.WriteLine("{0, -15} {1, -20} {2, -10}", city.getCityName(), city.getCityState(),
city.getPopulation());
}
}
class City
{
string cityName;
string cityState;
int population;

public City(string cityName, string cityState, int population)
{
this.cityName = cityName;
this.cityState = cityState;
this.population = population;
}
public string getCityName()
{
return cityName;
}
public string getCityState()
{
return cityState;
}
public int getPopulation()
{
return population;
}
public void setCityName(string cityName)
{
this.cityName = cityName;
}
public void setCityState(string cityState)
{
this.cityState = cityState;
}
public void setPopulation(int population)
{
this.population = population;
}
}
}
14y ago
Whether it is possible to alter this program to get output left align. Like as follows

Name                 State                 Population
-------                 ------                  -----------
Scarborough        Ontario 100000
Victoria               British_Columbia 700000
Kingston         Ontario 120000
Vancouver         British_Columbia 600000
14y ago
Thank you for your help.
Vulpes14y ago
Even though you're initializing the 3 fields in the constructor, this doesn't necessarily mean that you can't change them subsequently using 'set' methods which I think is what the program is trying to demonstrate:

using System;

namespace _4e7
{
class MovingHistory
{
static void Main(string[] args)
{
City myCity = new City("Scarborough","Ontario", 100000);
City myFriendCity = new City("Victoria", "British_Columbia",700000);
DisplayCity(myCity);
DisplayCity(myFriendCity);
myCity.setCityName("Kingston"); // say
myCity.setPopulation(120000);
myFriendCity.setCityName("Vancouver"); // say
myFriendCity.setPopulation(600000);
DisplayCity(myCity);
DisplayCity(myFriendCity);
Console.ReadKey();
}

static void DisplayCity(City city)
{
Console.WriteLine("Name = {0}, State = {1}, Population = {2}", city.getCityName(), city.getCityState(), city.getPopulation());
}
}
class City
{
string cityName;
string cityState;
int population;

public City(string cityName, string cityState, int population)
{
this.cityName = cityName;
this.cityState = cityState;
this.population = population;
}
public string getCityName()
{
return cityName;
}
public string getCityState()
{
return cityState;
}
public int getPopulation()
{
return population;
}
public void setCityName(string cityName)
{
this.cityName = cityName;
}
public void setCityState(string cityState)
{
this.cityState = cityState;
}
public void setPopulation(int population)
{
this.population = population;
}
}
}