Solved

Float or double to string....

Posted on 2002-05-05
11
244 Views
Last Modified: 2010-04-02
Hello Experts...

There is a library for converting integers to chars.
itoa....
But I didn't find any to do the same with noninteger numbers...
For instances... How can I convert the number 12.365 to a char array with "12.365"?.

If there is no function that Does that... I guess I will must write one....
How can I handle a double var?
I mean.... Is it right to say that the first four bytes contains the int part of the number and the last four bytes the decimal part?...

I need some help about this....

Thank you...
0
Comment
Question by:Marsc
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 3
  • 2
  • +2
11 Comments
 
LVL 86

Expert Comment

by:jkr
ID: 6990611
use either

/* _GCVT.C: This program converts -3.1415e5
 * to its string representation.
 */

#include <stdlib.h>
#include <stdio.h>

void main( void )
{
   char buffer[50];
   double source = -3.1415e5;
   _gcvt( source, 7, buffer );
   printf( "source: %f  buffer: '%s'\n", source, buffer );
   _gcvt( source, 7, buffer );
   printf( "source: %e  buffer: '%s'\n", source, buffer );
}


or

#include <sstream>

stringstream ss;
double d = 3.141;

ss << d;

const char* psz = ss.str().c_str();
0
 
LVL 86

Expert Comment

by:jkr
ID: 6990613
Ooops, correction - the latter sample should read

#include <sstream>
using namespace std;

stringstream ss;
double d = 3.141;

ss << d;

const char* psz = ss.str().c_str();
0
 
LVL 1

Accepted Solution

by:
Shivshankar earned 100 total points
ID: 6990993
I'd suggest you rather use sprintf.

sprintf(str, "%5.2f", some_float_number);

The simplest solution that I always use. More importantly I get it in whatever format I want. :-)
0
Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 1

Author Comment

by:Marsc
ID: 6991172
I cannot use printf... The program runs under Windows....
So.... I need the string to use the API DrawText ()....
I will see what is _gcvt about....

0
 
LVL 1

Expert Comment

by:jdrescher
ID: 6991245
> I cannot use printf... The program runs under Windows....
>So.... I need the string to use the API DrawText ()....

sprintf works fine under windows. Just sprintf to a buffer and use DrawText on that buffer.

char str[100];

sprintf(str, "%5.2f", some_float_number);

DrawText(hDC,str,strlen(str),rect,uFormat);

// see the doc for DrawText for a description of the params.



Are you using MFC. If so use the following;

//cdc is a CDC for the window you need to draw on.

CString str;

str.Format("%5.2f", some_float_number);

cdc.DrawText(str,rect,nFormat);



John
0
 
LVL 1

Expert Comment

by:Yechezkel
ID: 6993412
0
 
LVL 1

Author Comment

by:Marsc
ID: 7014651
All anwsers were good, but Shivshankar's was the first...

Thank you.
0
 
LVL 86

Expert Comment

by:jkr
ID: 7014681
>>but Shivshankar's was the first...

Accepted Answer
From: Shivshankar  Date: 05/06/2002 02:47AM PST  

Comment
From: jkr  Date: 05/05/2002 02:51PM PST  

That is a whole *day* later...
0
 
LVL 1

Author Comment

by:Marsc
ID: 7016376
jkr:

I am sorry about this.... You are right...
I always try to be fair but I mistaken about this...
Let me know if you want me to post some question with points for you.
0
 
LVL 1

Expert Comment

by:Shivshankar
ID: 7019660
Yes jkr,

I'm a day later than you.
But, I guess, its a simple and straightforward solution.

Best Regards.
0
 
LVL 1

Author Comment

by:Marsc
ID: 7022613
Shivshankar

If we talk about to be fair...
Actually you are right

:-)
0

Featured Post

Announcing the Most Valuable Experts of 2016

MVEs are more concerned with the satisfaction of those they help than with the considerable points they can earn. They are the types of people you feel privileged to call colleagues. Join us in honoring this amazing group of Experts.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Find Visual Studio Tools 2 136
Best book to learn C++ 4 97
Unable to start eclipse ? 17 175
COM server issue 2 29
Unlike C#, C++ doesn't have native support for sealing classes (so they cannot be sub-classed). At the cost of a virtual base class pointer it is possible to implement a pseudo sealing mechanism The trick is to virtually inherit from a base class…
What is C++ STL?: STL stands for Standard Template Library and is a part of standard C++ libraries. It contains many useful data structures (containers) and algorithms, which can spare you a lot of the time. Today we will look at the STL Vector. …
The viewer will learn how to use the return statement in functions in C++. The video will also teach the user how to pass data to a function and have the function return data back for further processing.
The viewer will learn how to clear a vector as well as how to detect empty vectors in C++.

751 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question