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

That is the structure that I created:

Code:

---

#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");


}

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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.

Code:

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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

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

Quote:

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Originally Posted by 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

---

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

Code:

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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 << " ";
                }
        }

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The code is wrong.

Quote:

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

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

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?

Quote:

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Originally Posted by 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?

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Sorry. I didn't understand what you mean.

Try this

Code:

---

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 << " ";
        }
}

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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.

Quote:

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Sorry. I didn't understand what you mean.

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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? :confused:

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.

Quote:

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I include string for case.

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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.

Quote:

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

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

...

Quote:

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

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Is this a homework exercise?

Quote:

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Originally Posted by fr4234

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

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Then that's how you code it.

Quote:

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Originally Posted by 2kaud

Is this a homework exercise?

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

Quote:

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Originally Posted by 2kaud

Then that's how you code it.

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Is it possible to do it with do while.

Quote:

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

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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! :thumbd:

Quote:

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Originally Posted by fr4234

Is it possible to do it with do while.

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Yes.

Well I do it like this:

Code:

---

char choose[1];
        do {
               
                       
                        cout << "New check? Y/N \n";
                        cin >> choose;
                        if (_stricmp("N", choose) == 0)
                        {
                                break;
                        }
                        char name_for_check[10];
                        cout << "\n Name for check:";
                        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 << endl;
                                }
                        }


       

        }
        while (_stricmp("Y", choose) == 0);
        system("pause");
}

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The code is working but after I run it it show this message:

Quote:

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Run-Time Check Failure #2 - Stack around the variable 'choose' was corrupted.

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As choose is defined to be a c-style string and not a char, then

Code:

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cin >> choose;

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is going to treat choose as a c-style array and terminate it with a null. This makes the string at least 2 chars but you have only allocated space for 1!

This is why using c-style strings in a c++ program is a bad idea Get your teacher to explain using the c++ string type.