conversion from double to char or string

Question

0.00/5 (No votes)

See more:

C++

How do i convert a double to 2 decimal places and display the output as string or char.

Thanks.

Posted 15-Oct-10 6:57am

slimtugo

Add a Solution

4 solutions

Solution 4

If displaying it to the console is the only desire, then just:
printf("%.2f\n", doubleVal);

If you want divide it into two part, just use modf function.

They are indeed two different tasks.

Posted 16-Oct-10 0:29am

Zhan Zongru

Solution 1

use the modf function. This splits your double into the integer part and the fractional part.

Then, take the fractional part and multiply it by a power of 10 in your case, 10^2. Then use the floor function to return just the integer portion of that number and then divide it by the power of 10. Then, add the integer and fractional parts back together.

C

double dblOriginal, dblIntPortion, dblFractPortion;
dblOriginal = 25.4938;

dblFractPortion = modf(dblOriginal, &dblIntPortion);

dblFractPortion = pow(10.0,2) * dblFractPortion;
dblFractPortion = floor(dblFractPortion);
dblFractPortion = dblFractPortion / pow(10.0,2);

cout << (dblIntPortion + dblFractPortion);

This should give you what you're looking for (though I'm a bit rusty on c++).

Posted 15-Oct-10 7:35am

William Winner

Updated 15-Oct-10 8:02am

v2

Solution 3

I would recommend using printf or sprintf

Posted 15-Oct-10 23:07pm

T2102

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Alain Rist · Accepted Answer · 2010-10-15T11:02:00

Using the standard library facilitation is simpler and more versatile:

C++

#include<iomanip>
#include<strstream>
#include<string>

// Converts a double to a string rounded to t_digits decimal positions
template <size_t t_digits>
std::string DoubleToString(double dVal)
{
    std::ostrstream oss;
    oss << std::fixed << std::setprecision(t_digits) << dVal << std::ends;
    return oss.str();
}

Test program:

C++

#include<iostream>
int main()
{
    std::cout << DoubleToString<2>(1234.) << std::endl;
    std::cout << DoubleToString<2>(1.1) << std::endl;
    std::cout << DoubleToString<2>(1234.5678) << std::endl;
    std::cout << DoubleToString<2>(1.2345678) << std::endl;
    std::cout << DoubleToString<4>(1.2345678) << std::endl;
}

cheers,
AR