Programming Forums > Application Development > C++

aShoe · Feb 18th, 2008, 6:58 PM

Can some one give me an idea of how to limit decimal spaces from a double.

dr.p · Feb 18th, 2008, 8:02 PM

aShoe, if you're using the iostream library for output, you need to use the setprecision() manipulator (http://cppreference.com/io_flags.html#manipulators).

Example:

(Toggle Plain Text)

#include <iostream>
#include <iomanip>
//...
float floatval = 4.026783;
std::cout << std::dec << std::setprecision(3) << floatval << std::endl;
// outputs "4.03"

Or, if you're using C style output:

(Toggle Plain Text)

#include <stdio.h>
//...
float floatval = 4.026783;
printf("%.2f\n", nfloat);
// outputs "4.03"

Ancient Dragon · Feb 18th, 2008, 8:05 PM

You can only limit them on output, such as with cout of another output stream

(Toggle Plain Text)

double x = 12.1234567890;
cout << setprecision(4) << width(4) << x << "\n";

has the following output

(Toggle Plain Text)

12.12
Press any key to continue . . .

[edit] I was too slow. what dr.p said[/edit]

Feb 18th, 2008, 6:58 PM	#1
aShoe Newbie Join Date: Feb 2008 Posts: 1 Rep Power: 0	limiting decimal places Can some one give me an idea of how to limit decimal spaces from a double.

Feb 18th, 2008, 8:02 PM	#2
dr.p Programmer Join Date: Feb 2006 Location: Ohio Posts: 93 Rep Power: 3	Re: limiting decimal places aShoe, if you're using the iostream library for output, you need to use the setprecision() manipulator (http://cppreference.com/io_flags.html#manipulators). Example: (Toggle Plain Text) #include <iostream> #include <iomanip> //... float floatval = 4.026783; std::cout << std::dec << std::setprecision(3) << floatval << std::endl; // outputs "4.03" #include <iostream> #include <iomanip> //... float floatval = 4.026783; std::cout << std::dec << std::setprecision(3) << floatval << std::endl; // outputs "4.03" Or, if you're using C style output: (Toggle Plain Text) #include <stdio.h> //... float floatval = 4.026783; printf("%.2f\n", nfloat); // outputs "4.03" #include <stdio.h> //... float floatval = 4.026783; printf("%.2f\n", nfloat); // outputs "4.03" __________________ Neeley.org

Feb 18th, 2008, 8:05 PM	#3
Ancient Dragon PFO God In Training Join Date: Jun 2005 Location: near St Louis, MO. (USA) Posts: 530 Rep Power: 4	Re: limiting decimal places You can only limit them on output, such as with cout of another output stream (Toggle Plain Text) double x = 12.1234567890; cout << setprecision(4) << width(4) << x << "\n"; double x = 12.1234567890; cout << setprecision(4) << width(4) << x << "\n"; has the following output (Toggle Plain Text) 12.12 Press any key to continue . . . 12.12 Press any key to continue . . . [edit] I was too slow. what dr.p said[/edit]

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Programming Forums > Application Development > C++

limiting decimal places