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String Input & Output

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Join Date: Oct 2007

Posts: 49

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nicz888

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String Input & Output

Dec 16th, 2007

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// Stopping input with an empty string
#include <iostream>
using namespace std;
#include <cstring>
 
int main()
{
    int i = 1;
    char temp[80];
	char string[80]; // room for 255 strings
 
 
    cout << "\n\nEnter some strings - (blank to exit)"
         << " \nfirst string: ";
    cin.getline(temp, 80);
    while (temp[0] != '\0')
    {
        cout << "String " << i << " : " << temp << "\nnext string: ";
        cin.getline(temp, 80);
        string == strcat(string," ");
		string == strcat(string,temp);
		i++;
 
    }
 
    cout << "\n\n";
 
	//for (int index = 0; index < i; index++)
    cout << string ;
 
}
// Stopping input with an empty string
#include <iostream>
using namespace std;
#include <cstring>

int main()
{
    int i = 1;
    char temp[80];
	char string[80]; // room for 255 strings
	

    cout << "\n\nEnter some strings - (blank to exit)"
         << " \nfirst string: ";
    cin.getline(temp, 80);
    while (temp[0] != '\0')
    {
        cout << "String " << i << " : " << temp << "\nnext string: ";
        cin.getline(temp, 80);
        string == strcat(string," ");
		string == strcat(string,temp);
		i++;

    }

    cout << "\n\n";
    
	//for (int index = 0; index < i; index++)
    cout << string ;

}

i updated the code

input: bill loves to eat
output: $ loves to eat

$ is a weird character that show up. i don't know what it is.

Last edited by nicz888; Dec 16th, 2007 at 9:54 pm.

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nicz888

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Re: String Input & Output

Dec 16th, 2007

Last edited by nicz888; Dec 16th, 2007 at 10:16 pm. Reason: warning are gone now

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nicz888

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Re: String Input & Output

Dec 16th, 2007

i notice that when i change the value in line 10.
string[x]

the output will change.
i input bill loves to eat
my output is @ loves to eat ??

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Duoas

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Re: String Input & Output

Dec 16th, 2007

You misunderstand something about pointers.

"temp" is an array of 80 characters. There is now space reserved in memory for 80 characters. The name "temp" by itself is a pointer to the first character in the array.

"array" is an array of 255 pointers to characters. There is now space reserved in memory for 255 pointers (not characters). The name "array" by itself is a pointer to the first pointer in the array. (BTW, don't name things "array".)

So, if you say strcpy( temp, "Hello" ); then the temp[] array contains the string "Hello".
If you then say strcpy( temp, "world" ); then the temp[] array contains the string "world". The string "Hello" is overwritten, and no longer exists.

In your loop, you assign array[ n ] (a pointer to a character) the address of the first char in the temp array. So,

 Help with Code Tags 
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strcpy( temp, "Hello" );  // temp[] contains "Hello"
array[ 0 ] = temp;
// array[ 0 ] points to "Hello" in temp[]
 
strcpy( temp, "world" );  // temp[] contains "world"
// array[ 0 ] still points to temp[], but temp[] now
// contains "world"
strcpy( temp, "Hello" );  // temp[] contains "Hello"
array[ 0 ] = temp;
// array[ 0 ] points to "Hello" in temp[]

strcpy( temp, "world" );  // temp[] contains "world"
// array[ 0 ] still points to temp[], but temp[] now
// contains "world"

Your loop is failing because "i" starts at one when it should start at zero. In other words, when you increment "i" you are saying that there is one more item in the "array" than there really is.

Hope this helps.

[EDIT] You know, it really is difficult to help when you change things after posting.
I'll check again after you've made up your mind.

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nicz888

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Re: String Input & Output

Dec 16th, 2007

sorry about changing my original post

i think i fix the first problem i have and now this weird character that is showing up, how do i fix that?

Last edited by nicz888; Dec 16th, 2007 at 10:03 pm.

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nicz888

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Re: String Input & Output

Dec 16th, 2007

i notice that i can change both line 20 and 21 to
strcat_s(string, " ");
and
strcat_s(string, temp);
that will get rid of all the warnings.

and the result is the same.
but my "bill" is still not showing up, why?

Last edited by nicz888; Dec 16th, 2007 at 10:10 pm.

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Duoas

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Re: String Input & Output

Dec 16th, 2007

char string[80]; only creates an array of 80 characters. The array is named "string".

There is a problem with the order in which you are doing things. You get another string from the user before you copy "bill" to the "string" array.

The weird character is because you did not initialize your "string" array properly. You are lucky the program didn't crash.

Somewhere at the top, say line 11 or so, say
string[0] = '\0';

Hope this helps.

PS. Don't name arrays "string" either. Come up with a real name.

[EDIT] Oh yeah, strcat_s() is non-standard MS crap. If you are only going to use the MS compiler, then fine, else stick with strcat().

Last edited by Duoas; Dec 16th, 2007 at 10:18 pm.