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Floating point numbers

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Join Date: Sep 2004

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Narue

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Re: Floating point numbers

#11

Jan 1st, 2005

>just wondering if you can split up a string of numbers?
Of course:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
#include <string>
 
using namespace std;
 
int main()
{
  string source = "123.456";
  string a, b;
 
  a = source.substr(0, source.find('.'));
  b = source.substr(source.find('.') + 1);
 
  cout<< a <<'\n'<< b <<endl;
}
#include <iostream>
#include <string>

using namespace std;

int main()
{
  string source = "123.456";
  string a, b;

  a = source.substr(0, source.find('.'));
  b = source.substr(source.find('.') + 1);

  cout<< a <<'\n'<< b <<endl;
}

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happyHour

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Re: Floating point numbers

#12

Jan 1st, 2005

umm, we havent been taught that way, is they not a for loop i could use to tell it to stop... ie

for (int i = 0; i !='.'; i++ )

i know that does work but something amounst those lines?

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Narue

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Re: Floating point numbers

#13

Jan 1st, 2005

>umm, we havent been taught that way
So!? There are plenty of ways to do what you want that you probably haven't been taught. I'm here to teach, so what's the problem? If you don't try to broaden your horizons you'll never get anywhere, and if you stick to what you've been taught then you'll be writing C++ with the least useful (and flexible, and powerful) subset of features imaginable.

>i know that does work but something amounst those lines?
Yes, it does work. But since you don't want to learn anything new, you might as well use it:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
 
using namespace std;
 
int main()
{
  const char *source = "123.456";
  char a[4], b[4];
  int i = 0, j;
 
  for (j = 0; j < 3 && source[i] != '.'; j++)
    a[j] = source[i++];
  a[j] = '\0';
  ++i;
  for (j = 0; j < 3 && source[i] != '\0'; j++)
    b[j] = source[i++];
  b[j] = '\0';
 
  cout<< a <<'\n'<< b <<endl;
}
#include <iostream>

using namespace std;

int main()
{
  const char *source = "123.456";
  char a[4], b[4];
  int i = 0, j;

  for (j = 0; j < 3 && source[i] != '.'; j++)
    a[j] = source[i++];
  a[j] = '\0';
  ++i;
  for (j = 0; j < 3 && source[i] != '\0'; j++)
    b[j] = source[i++];
  b[j] = '\0';

  cout<< a <<'\n'<< b <<endl;
}

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happyHour

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Re: Floating point numbers

#14

Jan 1st, 2005

Cool, that looks good, but if a user wanted to enter data into the array, since you've used a const pointer to an array of characters it wouldnt work would it? but upon taking out the const and adding cin >> *source that still doesnt work... I'm back in the text book looking for a visual aid...

here what i cam up with on the top of my head...

[php]

char thesting[8];
cin << the string

char *value
*value = ( thestring)

[/php]

not sure if that works though

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1o0oBhP

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Re: Floating point numbers

#15

Jan 1st, 2005

if it doesnt try value = &thestring. that is the way to reference a pointer

http://sales.carina-e.com

no www
no nonsense

coming soon to a pc near you! :cool:

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happyHour

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Re: Floating point numbers

#16

Jan 1st, 2005

•

Originally Posted by 1o0oBhP

if it doesnt try value = &thestring. that is the way to reference a pointer

I get a load of garbage which is already in memory with this code:

[php]
char string;
const char *source ;

source = &string;

cin >> string;

char a[4], b[4];
int i = 0, j;

for (j = 0; j < 3 && source[i] != '.'; j++)
a[j] = source[i++];
a[j] = '\0';
++i;
for (j = 0; j < 3 && source[i] != '\0'; j++)
b[j] = source[i++];
b[j] = '\0';

cout<< a <<'\n'<<"0."<< b <<endl;

return 0;
[/php]

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Narue

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Re: Floating point numbers

#17

Jan 1st, 2005

string isn't a string, it's a character. Because a C-style string is required to be terminated by '\0', and cin's >> operator won't add that when extracting to a character, your loop will go until it finds one. The end result is that you're invoking undefined behavior by accessing memory you don't own. The solution is a quick and simple change:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
char string; 
const char *source ; 
 
source = &string;
char string; 
const char *source ; 

source = &string;

becomes

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
char string[8];     // Make it a string
const char *source ; 
 
source = string;     // & is no longer needed
char string[8];     // Make it a string
const char *source ; 

source = string;     // & is no longer needed

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happyHour

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Re: Floating point numbers

#18

Jan 1st, 2005

intresting, is they anyway i can deeper understand these pointers? I get everything else i've been taught but hate to use pointers since i don't know how to use them... A nice tutorial with examples would be nice to read...

could anyone recommend any?

Naure >> Thanks for the code and assiatnce along with all the rest who posted...really appricated

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Narue

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Re: Floating point numbers

#19

Jan 1st, 2005

>could anyone recommend any?
Clikey.

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happyHour

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Re: Floating point numbers

#20

Jan 1st, 2005

upon trying to make the code more powerful ....

int n = 0;
if ( string[n] < 0 )
{
cout << "The sign is: -" << '\n';
}
else
{
cout << "The sign is: +" << '\n';
}

i included that however fo some reason its always a +!! so i thought if we could keep this float value[3]; and change it to an string.... just googling that now