learning to use arrays and C-strings together

Hi

1: I don't understand how one could enter the all the elements on a character array with one cin. This seeming works as is shown in the OUTPUT code at the bottom.

One need to use cin.get() when there is a white space between the elements because white space is taken to be a null character which signals the end of the string.

2: Why doesn't the for loop work? Why do I have to enter the array element in a column form?

3: Is "C" in cin.get() always the size of the array?

Code:

// read_your_name.cpp
// read and print your name using an array and using
// cin, for loop, cin.get()

#include <iostream>
#include <cstdlib>
#include <cstring>

using namespace std;

const int C = 20;

int main()
{
        int i;

        char name[C];

        cout << "enter your name: ";
        cin >> name;

        cout << "your name is: Mr. " << name << endl;


        cout << "enter your name: ";

        for (i=0; i<C; i++)
        {
                cin >> name[i];
                cin.ignore();
        }

        cout << "your name is: Mr. ";

        for (i=0; i<C; i++)
        {
                cout << name[i];
        }


        cout << "\nenter your name: ";
        cin.get(name, C);

        cout << "your name is: Mr. " << name << endl;

        system("pause");
        return 0;
}

OUTPUT

Code:

enter your name: jackson
your name is: Mr. jackson
enter your name: j
a
c
k
s
o
n
1
1
1
1
1
1
1
1
1
1
1
1
1
your name is: Mr. jackson1111111111111enter your name: jackson heights
your name is: Mr. jackson heights
Press any key to continue . . .

2. because you're telling it to read a character. istream:perator>> - C++ Reference

you're instructing it to read a character (by invoking the char& overload of >>)

3. again, refer to the documentation: istream::get - C++ Reference


the BEST thing you can do is to always read the docs first. i know as a beginner it's not very accessible, but to master the art of reading code documentation is to empower yourself to quickly learn new technologies. always always ALWAYS read the docs first, and ask questions about what you don't understand in them second. imo, this is the fast-track to becoming a proficient programmer.

Originally Posted by jackson6612

1: I don't understand how one could enter the all the elements on a character array with one cin. This seeming works as is shown in the OUTPUT code at the bottom.

What are you confused about? You already input a name in one statement with the std::cin >> name.
Btw, never ever do that. This is prone to buffer overflows and is as bad as gets.
Instead, use std::cin.getline.

One need to use cin.get() when there is a white space between the elements because white space is taken to be a null character which signals the end of the string.

Where is the question?

2: Why doesn't the for loop work? Why do I have to enter the array element in a column form?

The loop works perfectly. Remember that std::cin is line buffered. That is, it only returns after you've pressed enter. So each std::cin statement in the loop wants a newline before it returns.

3: Is "C" in cin.get() always the size of the array?

No, it is the number of elements you want to read from the stream. Make sure this is equal to or less than the array size.

Originally Posted by jackson6612

Hi

1: I don't understand how one could enter the all the elements on a character array with one cin. This seeming works as is shown in the OUTPUT code at the bottom.

One need to use cin.get() when there is a white space between the elements because white space is taken to be a null character which signals the end of the string.

2: Why doesn't the for loop work? Why do I have to enter the array element in a column form?

3: Is "C" in cin.get() always the size of the array?

Include the string.h library and declare the array as a string. By doing this you will have a multi-character for each position of the array.

Thank you, m37hod.

Originally Posted by Elysia

What are you confused about? You already input a name in one statement with the std::cin >> name.
Btw, never ever do that. This is prone to buffer overflows and is as bad as gets.
Instead, use std::cin.getline.

Thanks a lot, Elysia. Yes, I'm confused because I don't really know what I'm doing.

I'm surprised that I was able to input values for all the array elements with one cin. But it seems it would only work for arrays of char type. It wouldn't work for an array of int type. Why I think so? An element of array of char type could obvious hold only one digit (such as '1', '2', '3', etc.) or one character (such as 'a', 'A', 'c', etc.); in other words the 'size' of the element in this case is fixed. But for an element of array type int type the 'size' is not fixed. So, probably, when we input values for an array of char type, when we have entered one character with cin, we have already entered second element, and so on.

Originally Posted by Elysia

The loop works perfectly. Remember that std::cin is line buffered. That is, it only returns after you've pressed enter. So each std::cin statement in the loop wants a newline before it returns.

Is there any way to make it so that I can input values in a row rather than a column?

Originally Posted by jackson6612

I'm surprised that I was able to input values for all the array elements with one cin. But it seems it would only work for arrays of char type. It wouldn't work for an array of int type. Why I think so? An element of array of char type could obvious hold only one digit (such as '1', '2', '3', etc.) or one character (such as 'a', 'A', 'c', etc.); in other words the 'size' of the element in this case is fixed. But for an element of array type int type the 'size' is not fixed. So, probably, when we input values for an array of char type, when we have entered one character with cin, we have already entered second element, and so on.

It has nothing to do with that.
Strings are an exception, and that is all.

Is there any way to make it so that I can input values in a row rather than a column?

You use std::cin.getline or std::getline instead of std::cin >>.

Thank you, Elysia.

What's the difference between cin.get() and cin.getline()? In the code below I could have used cin.get with the same effect.

Code:

// istream getline
#include <iostream>
using namespace std;

int main () {
  char name[256], title[256];

  cout << "Enter your name: ";
  cin.getline (name,256);

  cout << "Enter your favourite movie: ";
  cin.getline (title,256);

  cout << name << "'s favourite movie is " << title;

  return 0;
}

Perhaps you should read the documentation: istream - C++ Reference

Hi Elysia

I have been to that resource but just got more confused. So, if it's possible, let me have some information about the difference between the two. Thanks.

Originally Posted by godly 20

Include the string.h library and declare the array as a string. By doing this you will have a multi-character for each position of the array.

including string.h will only get you c-style string functions. the thing to do (unless you're using an ancient compiler like borland or VC++ 4) is include <string>

all of the standard C++ headers nowadays have no .h extension.

i dont think cin.get will give you the same effect as cin.getline gives.
because cin.get will not capture the \n entered in the first input to the name.

have you tried?

The results are weird. Here is the code and the output.

Code:

// get_and_getline.cpp
// difference between cin.get() and cin.getline()

#include <iostream>
#include <cstdlib>
#include <cstring>

using namespace std;

int main()
{
        const int C = 10;

        char str[C];

        cout << "enter your name: ";
        cin.get(str, C);

        cout << "your name is: " << str << endl;

        cout << "enter your name again: ";
        cin.getline(str, C);

        cout << "your name is: " << str << endl;

        system("pause");
        return 0;

}

OUTPUT

Code:

enter your name: jackson
your name is: jackson
enter your name again: your name is:
Press any key to continue . . .

Originally Posted by jackson6612

Hi Elysia

I have been to that resource but just got more confused. So, if it's possible, let me have some information about the difference between the two. Thanks.

So what you're saying is that you can't read plain English, but you want us to write more English to tell you what the other English said?

Originally Posted by jackson6612

The results are weird. Here is the code and the output.

The results are weird because you did not read the documentation.
std::cin.get does not extract the newline from the buffer.
std::cin.getline does extract the newline from the buffer and discard it.