c++ Structures export data for specific name, country, last name

[fr4234]

That is the structure that I created:

#include <iostream>
#include <string>
#include <fstream>
using namespace std;


struct Students
{
	char first_name[10];
	char last_name[10];
	char country[20];


};
int main()
{
	Students array[10];
	int n, i;
	cin >> n;

	for (i = 0; i < n; i++)
	{
		cout << "Name:";
		cin >> array[i].first_name;
		cout << "Last Name:";
		cin >> array[i].last_name;
		cout << "Country:";
		cin >> array[i].country;

	}

	for (i = 0; i < n; i++)
	{
		cout << array[i].first_name << " ";
		cout << array[i].last_name << " ";
		cout << array[i].country << " ";


	}
	system("pause");


}

And I have to write code that once I enter John (for example) displays all information about him: last name, country. And when I enter country to export: first name, last name. Maybe I don't explain it properly. Because my english is bad. Maybe that's the reason that i can't find specific information or similar examples.

Ouput example:
n=2
Name:John
Last Name: Doe
Country: England
 
Name:Pete
Last Name: Donaldson
Country: USA

Name:John
Last Name: Peterson
Country: England
 

 
And that's the part that i can't do:
 
/Info about student/
Enter Name for check:
John
 
and here the output must be:
Name:John
Last Name: Doe
Country: England

Name:John
Last Name: Peterson
Country: England
 
another check: 
if I enter Pete:
Name:Pete
Last Name: Donaldson
Country: USA

The same think for country, when if I enter England:
Name:John
Last Name: Doe
Country: England

Name:John
Last Name: Peterson
Country: England

[2kaud]

You need to iterate the array comparing the input data to the required data of the array element and if a match is found then display the contents of the array element. As you are using c-style strings, use strcmp() to compare. See https://msdn.microsoft.com/en-us/library/e0z9k731.aspx

[fr4234]

You need to iterate the array comparing the input data to the required data of the array element and if a match is found then display the contents of the array element. As you are using c-style strings, use strcmp() to compare. See https://msdn.microsoft.com/en-us/library/e0z9k731.aspx

Thank you 2kaud. I try something. It looks silly but only this I managed to make.

for (i = 0; i < n; i++)
	{
		char name_for_check;
		cin >> name_for_check;
		if (strcmp(array[i].first_name, name_for_check) == 0)
		{
			cout << array[i].first_name << " ";
			cout << array[i].last_name << " ";
			cout << array[i].country << " ";
		}
	}

The code is wrong.

Error C2664 'int strcmp(const char *,const char *)': cannot convert argument 2 from 'char' to 'const char *' 45

But I don't think that this is the only mistake.

[laserlight]

name_for_check is only a char, so it cannot store a string for the name to check.

Why are you not using std::string objects?

[fr4234]

name_for_check is only a char, so it cannot store a string for the name to check.

Why are you not using std::string objects?

Sorry. I didn't understand what you mean.

[2kaud]

Try this

char name_for_check[10];
cin >> name_for_check;
for (i = 0; i < n; i++)
{
	if (strcmp(array[i].first_name, name_for_check) == 0)
	{
		cout << array[i].first_name << " ";
		cout << array[i].last_name << " ";
		cout << array[i].country << " ";
	}
}

You need to ask for the input outside of the loop and make name_for_check a char array the same size as the struct element to check.

Sorry. I didn't understand what you mean.

In c++, c-style strings are very rarely used as c++ has its own string type. One of the issues with using c-style strings is that you have specified the maximum size of the array as 10 for the first_name. This means that the maximum number of chars in the name can be only 9 (as the terminating NULL takes one position). If you enter more than 9 chars then this will be accepted but the code will overwrite what ever happens to be in memory - causing unwanted and undefined behaviour. This is called buffer overflow and is the siurce of many 'security type issues' within code.

Using the c++ string type this problem is avoided as you don't need to pre-allocate the size of the strings. See http://www.cplusplus.com/reference/string/string/ for more details.

NB You have the include for string in the code, so why not use it?

[fr4234]

I include string for case.
And I do not know how to do it with string objects...
Your suggestion works.
Do you have an idea how to do so that I can make an unlimited number of requests for name_for_check.

[2kaud]

I include string for case.

No. You are including the c++ string type. For c-style strings you should include cctype if you want to use the c-style case functions.

Do you have an idea how to do so that I can make an unlimited number of requests for name_for_check.

Yes - put the request for the name and the check within another loop. What will be the loop exit condition?

[fr4234]

...

[2kaud]

And I do not know how to do it with string objects...

Is this a homework exercise?

[2kaud]

I think it should exit if there is no student with that name.

Then that's how you code it.

[fr4234]

Is this a homework exercise?

Not exactly. My homework is more complex, but this would help me somewhat.

[fr4234]

Then that's how you code it.

Is it possible to do it with do while.

[2kaud]

And I do not know how to do it with string objects...

Then ask your teacher why you are being taught/asked to use c-style strings rather than the c++ string type? If you are learning c++ then you should be taught the c++ way - and that means c++ type string and not c-style strings. Black mark to teacher!

[2kaud]

Is it possible to do it with do while.

Yes.