Отправлено: 05.07.14 09:37. Заголовок: how to find float decimal palce

i like to compare two float value the decimal place are matching
eg float values 0.02541 , 0.06541 . if i multiply one of this value like --> 0.02541 * 100000 = 2541 so this value have 4 decimal place how can i find this

 Отправлено: 06.07.14 09:50. Заголовок: solved

i wrote this code . is this code good or bad is there any better way to do this

#include <iostream>
#include <sstream>
using namespace std;

int main () {

float val =1.1006;
val = val*10000;

cout<<val<<endl;
stringstream ss (stringstream::in | stringstream::out);

ss << val;

string test = ss.str();

cout << test <<endl;
std::cout << "The size of str is " << test.size() << " bytes.\n";

return 0;
}

 Отправлено: 08.07.14 01:18. Заголовок: The code is compiled..

The code is compiled successfully but it is not clear what you are trying to achieve.

 Отправлено: 08.07.14 08:18. Заголовок: i am tying to compar..

i am tying to compare two float value that have same decimal place like this --> 0.12451 value have 5 decimal value ,---> this 0.00214 value have 3 decimal . i like to know is there any other way to do this

 Отправлено: 08.07.14 14:56. Заголовок: I have not understoo..

I have not understood what you mean saying that 0.00214 has 3 decimal.

Maybe you will find function modf declared in header cmath useful for yourself. It allows to extract the fraction of a floating number. For example

 
 #include <iostream>  
 #include <cmath> 
   
  
  int main ()  
  { 
 	double val = 1.1006;  
 		 
 	double ipart; 
 		 
 	double fpart = std::modf( val, &ipart ); 
 		 
 	std::cout << ipart << '\t' << fpart << std::endl; 
  
 	return 0;  
  } 
 

The output is

 
 1	0.1006 
 

 Отправлено: 08.07.14 18:36. Заголовок: no this is not i ne..

no this is not i needed . in my way you can see (above code) that i first multiply value like 0.00214 * 100000 = 214 i multiply to remove unwanted zero from value then i want to count how many value position like 0th , 10th, 100th, or 1000th in this case 214 is 100th so it is 3 . then i want to compare check to next value that is matching or not

above code that i convert float to string and use .size() operator to find this value. i like to know any better way to do this

 Отправлено: 09.07.14 21:15. Заголовок: Instead of std::stri..

Instead of std::stringstream you could use function std::to_string.

 Отправлено: 10.07.14 11:15. Заголовок: :sm36: ..

 Отправлено: 13.07.14 15:51. Заголовок: float to string convertion precision

std::stringstream & std::to_string are working correct . but when i input big precision value like float a = 3.141593254 its rounding value 3.14159 so it's not converting full float value to string i need 11 value precision and i can't use std::to_string becouse its c++ 11 fetures

 Отправлено: 14.07.14 14:41. Заголовок: The problem is that ..

The problem is that float numbers of type float are outputed with 6 decimal digits while float numbers of type double are outputed with 15 decimal digits.

Consider the following code

 
 #include <iostream> 
 #include <iomanip> 
 #include <limits> 
  
  
 int main()  
 { 
 	float    a = 3.141593254; 
 	double b = 3.141593254; 
 		 
 	std::cout << std::numeric_limits<float>::digits10 << std::endl; 
 	std::cout << "a = "  
 	          << std::setprecision( std::numeric_limits<float>::digits10 ) 
 	          << a << std::endl; 
 	std::cout << std::numeric_limits<double>::digits10 << std::endl; 
 	std::cout << "b = "  
 	          << std::setprecision( std::numeric_limits<double>::digits10 ) 
 	          << b << std::endl; 
 	 
 	return 0; 
 } 
 

The output is

 
 6 
 a = 3.14159 
 15 
 b = 3.141593254 
 

Take into account that in this statement

 
 float    a = 3.141593254; 
 

the float literal used as initializer has type double while variable a has type float. So there is a loss of precision.

 Отправлено: 14.07.14 22:14. Заголовок: i need to do this in..

i need to do this in float because my array data , i accessing like const float* rIn = in[rchan] + x; i believe this is 32 bit float array
is there any other way of doing this
i tried to convert float to string and float to char array both code working but it did not get 11 precision

all i want to do is look in the float value a left to right a = 0.001590254; in this case 0 to 4 and remove all the zero until any other value found and count how many digits in there so in this --> (1590254) 1 to 4 is the 7 digits size i like to get this size

 Отправлено: 14.07.14 22:42. Заголовок: data type float has ..

data type float has a restriction on the number of decimal digits it can store. If you have an array of float numbers then it can not represent exactly values as 0.001590254.

 Отправлено: 15.07.14 08:26. Заголовок: so i need to find ot..

so i need to find other way