DaniWeb Forum Index > Software Development > C++

count digits in string

Please support our C++ advertiser: Programming Forums - DaniWeb Sister Site

•

Join Date: Aug 2008

Posts: 31

Reputation: timb89 is an unknown quantity at this point

Solved Threads: 0

timb89

Offline

Light Poster

count digits in string

Jun 18th, 2009

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
int countDigits(string word)
{
    int count = 0;
 
    for (int i = 0; i < word.size(); i++)
    {    
        if (word.at(i) < 57 && word.at(i) > 49)
        {
            count++;
        }
    }
}
int countDigits(string word)
{
    int count = 0;
    
    for (int i = 0; i < word.size(); i++)
    {    
        if (word.at(i) < 57 && word.at(i) > 49)
        {
            count++;
        }
    }
}

i want to count the digits in a string "abc123". i know my problem is in the if statemnt i just cant get it working

stupid question i know im just stuck

Last edited by timb89; Jun 18th, 2009 at 11:43 pm.

•

Join Date: Aug 2005

Posts: 15,656

Reputation: Ancient Dragon has a reputation beyond repute

Solved Threads: 1500

Ancient Dragon Ancient Dragon is online now

Online

Still Learning

Re: count digits in string

Jun 19th, 2009

you can use the macro isdigit() to find out if it is '0' to '9'. And the At() method is unnecessary.

if( isdigit(word[i]) )

Last edited by Ancient Dragon; Jun 19th, 2009 at 12:18 am.

•

Join Date: Feb 2009

Posts: 1,969

Reputation: tux4life has a reputation beyond repute

Solved Threads: 214

tux4life

Offline

Posting Virtuoso

Re: count digits in string

Jun 19th, 2009

•

Originally Posted by Ancient Dragon

you can use the macro isdigit() to find out if it is '0' to '9'. And the At() method is unnecessary.

if( isdigit(word[i]) )

Is isdigit a macro then?
According to this information it isn't

"Never argue with idiots, they just drag you down to their level and then beat you with experience."

•

Join Date: May 2006

Posts: 3,128

Reputation: WaltP has much to be proud of

Solved Threads: 283

WaltP

Online

Posting Sensei

Re: count digits in string

Jun 19th, 2009

Change your comparison to
if (word[i] < 57 && word[i] > 49)

Also, the line is better written as
if (word[i] > 49 && word[i] < 57)
It's a more logical order for the comparison pair.

The 3 Laws of the Procrastination Society:
1) Never do today that which can be put off until tomorrow
2) Tomorrow never comes

•

Join Date: Feb 2009

Posts: 1,969

Reputation: tux4life has a reputation beyond repute

Solved Threads: 214

tux4life

Offline

Posting Virtuoso

Re: count digits in string

Jun 19th, 2009

•

Originally Posted by WaltP

Change your comparison to
if (word[i] < 57 && word[i] > 49)

Also, the line is better written as
if (word[i] > 49 && word[i] < 57)
It's a more logical order for the comparison pair.

Yes, but isn't the isdigit function a bit easier to work with?
However if he isn't allowed to use that function it would seem more logical to me if he'd written it like you did

Last edited by tux4life; Jun 19th, 2009 at 3:30 am.

"Never argue with idiots, they just drag you down to their level and then beat you with experience."

•

Join Date: Dec 2007

Posts: 360

Reputation: jencas is just really nice

Solved Threads: 69

jencas

Offline

Posting Whiz

Re: count digits in string

Jun 19th, 2009

And why 49 and 57 instead of '0' and '9'??? Are you training for an obfuscation contest?

If you are forced to reinvent the wheel at least try to invent a better one!

Please use code tags - Please mark solved threads as solved

•

Join Date: Feb 2009

Posts: 1,969

Reputation: tux4life has a reputation beyond repute

Solved Threads: 214

tux4life

Offline

Posting Virtuoso

Re: count digits in string

Jun 19th, 2009

•

Originally Posted by jencas

And why 49 and 57 instead of '0' and '9'??? Are you training for an obfuscation contest?

Agreed, '0' and '9' makes your code more readable, but the OP started with using the ASCII codes

But this is actually not a good reason to avoid this I think

Last edited by tux4life; Jun 19th, 2009 at 4:01 am.

"Never argue with idiots, they just drag you down to their level and then beat you with experience."

•

Join Date: Apr 2009

Posts: 22

Reputation: Alicito is an unknown quantity at this point

Solved Threads: 0

Alicito

Offline

Newbie Poster

Re: count digits in string

Jun 19th, 2009

I would solve it in this efficient easy way

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
#include <string>
using namespace std;
 
int countdigits(string word)
{
	int count=0;
	for(int i=0;i<(int)word.length();i++)
	{
		if(isdigit(word[i]))
			count=count+1;
	}
	return count;
}
void main()
{
	string word;
	getline(cin,word);
	int digits=0;
	digits=countdigits(word);
	cout<< digits<<endl;
}
#include <iostream>
#include <string>
using namespace std;

int countdigits(string word)
{
	int count=0;
	for(int i=0;i<(int)word.length();i++)
	{
		if(isdigit(word[i]))
			count=count+1;
	}
	return count;
}
void main()
{
	string word;
	getline(cin,word);
	int digits=0;
	digits=countdigits(word);
	cout<< digits<<endl;
}

Last edited by Ancient Dragon; Jun 19th, 2009 at 10:19 am. Reason: add code tags, remove color and bold tags

él¡é

•

Join Date: Dec 2007

Posts: 360

Reputation: jencas is just really nice

Solved Threads: 69

jencas

Offline

Posting Whiz

Re: count digits in string

Jun 19th, 2009

•

Originally Posted by tux4life

Agreed, '0' and '9' makes your code more readable, but the OP started with using the ASCII codes
But this is actually not a good reason to avoid this I think

I didn't quote your answer because my answer was intended to address the TO.

If you are forced to reinvent the wheel at least try to invent a better one!

Please use code tags - Please mark solved threads as solved

•

Join Date: Aug 2005

Posts: 15,656

Reputation: Ancient Dragon has a reputation beyond repute

Solved Threads: 1500

Ancient Dragon Ancient Dragon is online now

Online

Still Learning

Re: count digits in string

#10

Jun 19th, 2009

•

Originally Posted by tux4life

Is isdigit a macro then?
According to this information it isn't

Its probably implementation dependent. You have to check your compiler's ctype.h header file to find out whether its implemented as a macro or a function. The link you posted doesn't say one way or the other.