entering a string using for loop, "¶"

Hi

In the code below both blue cout statements should produce the same result because in both cases name[] variable is being worked on. But you see in one case I get this "¶". Why is so? Please let me know. Thanks.

When a string is entered using cin a space is considered to be end of a string. While entering the name using the for loop I inserted two spaces but they were ignored. Why is so?

Please help me. Thanks.

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>
#include <string>

using namespace std;

const int C = 20;

int main()
{
        int i;
        char name[C];
        string urname;

        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 << endl;

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


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

        cout << "enter your name: ";
        getline(cin, urname);

        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
   //space
h
e
i
g
h
t
s
  //space
0
0
0
0
0
0
your name is: Mr. jacksonheights000000
your name is: Mr. jacksonheights000000¶

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

1. Which part of "put a @$#%!@#$!@#$ \0 character at the end of your string" do you continually fail to understand?

2. You correctly note that spaces are ignored; then ask why, when you type spaces, they are ignored? Why do you ask this question?

Hi

Originally Posted by tabstop

1. Which part of "put a @$#%!@#$!@#$ \0 character at the end of your string" do you continually fail to understand?

Both of these:

Code:

your name is: Mr. jacksonheights000000
your name is: Mr. jacksonheights000000¶

are couts of the same variable. The first one results from using the for loop, and the second one using the 'normal' cout. I wanted to know that why do I get "¶" when the variable name[] is worked on by 'normal' cout?

2. You correctly note that spaces are ignored; then ask why, when you type spaces, they are ignored? Why do you ask this question?[/QUOTE]
I asked because in normal cases when an array is entered using cin the portion of the string entered after pressing space is ignored. But here space is ignore but the portion entered after space is not ignored.

Because you didn't put a \0 character at the end of your string. The first time you did not print the string, you printed a bunch of individual characters. The second time you printed the string. When you print a C-string, it goes until it finds a \0 character. If you didn't put one in (and you didn't), then it's going to keep walking. You must lead a charmed life, because you again only have one extra character instead of screenful after screenful of garbage. But you must put a \0 character at the end of your C-string. It is not optional.

2. C++ ignores all spaces at the beginning of input (spaces = the big long bar at the bottom of the keyboard, the tab key, and the enter-key). So your space was ignored, your enter key was ignored, and finally once you typed a letter it actually accepted the input.

Originally Posted by tabstop

Because you didn't put a \0 character at the end of your string. The first time you did not print the string, you printed a bunch of individual characters. The second time you printed the string. When you print a C-string, it goes until it finds a \0 character. If you didn't put one in (and you didn't), then it's going to keep walking. You must lead a charmed life, because you again only have one extra character instead of screenful after screenful of garbage. But you must put a \0 character at the end of your C-string. It is not optional.

2. C++ ignores all spaces at the beginning of input (spaces = the big long bar at the bottom of the keyboard, the tab key, and the enter-key). So your space was ignored, your enter key was ignored, and finally once you typed a letter it actually accepted the input.

Thanks a lot, tabstop.

Yes, I didn't put a \0 at the end because I was wrongly under the impression the impression that the compiler would insert it automatically. Although, I think, the compiler automatically inserts a \0 character but it requires that you haven't overrun the string's limit.

If you do character-by-character input, then the compiler is not going to treat the data as a string, because you are explicitly telling it not to. In that case, you are responsible for all the characters.

Code:

cin >> name;

How many times do we have to tell you to not do that?

Hi Elysia

Originally Posted by Elysia

Code:

cin >> name;

How many times do we have to tell you to not do that?

You mean I should have used cin.getline() or cin.get() instead? Please let me know this know, then I won't repeat this mistake again. Thanks.

Yeah, get and getline are safe to use. You could use cin >> setw(C-1) >> name, but the other functions are easier.

Originally Posted by King Mir

Yeah, get and getline are safe to use. You could use cin >> setw(C-1) >> name, but the other functions are easier.

Hi King Mir

Please have a look on the code below. Shouldn't it be

Code:

cin >> setw(MAX-1) >> str;

? Please guide me on this. Thanks.

Code:

/ safetyin.cpp
// avoids buffer overflow with cin.width
#include <iostream>
#include <iomanip>                  //for setw
using namespace std;

int main()
   {
   const int MAX = 20;              //max characters in string
   char str[MAX];                   //string variable str

   cout << "\nEnter a string: ";
   cin >> setw(MAX) >> str;         //put string in str,
                                    // no more than MAX chars
   cout << "You entered: " << str << endl;  
   return 0;
   }