This question already has answers here:
How do I print a double value with full precision using cout?
(17 answers)
Printing the correct number of decimal points with cout
(13 answers)
c++ cout << [double] not printing decimal places
(2 answers)
Closed 3 years ago.
setlocale(LC_ALL, "Portuguese");
double var = 1.0;
cout << var << endl;
system("pause");
return 0;
output:
1
Press any key to continue . . .
float and double only represent the values of numbers. “1” and “1.0” are both numerals for the same number, so 1 is the correct value of the var you set to 1.0. float and double do not represent the original numerals used to set their values, nor do they represent how much accuracy (relative to some ideal mathematical value) is present. The “1” you see as output is a result of default formatting. Other formatting options are available, but you must specify them yourself.
Related
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Round double to 3 points decimal [duplicate]
(4 answers)
Closed 4 months ago.
The community reviewed whether to reopen this question 4 months ago and left it closed:
Original close reason(s) were not resolved
With a function, I'm getting these values.. 0.07, 0.038, 0.072, 0.078. Now, I'm trying to apply round of to these values so that they should return like this.
round(val, decimal_place). So that, 0.038 value should return as 0 and rest should come as 0.1. (I can do it using an if condition like limiting with <0.5>. But, want to know. Is there any such function is there in C++ which limit decimal places below 0.5.
It's there in VB by doing like this I think. roundof(value, decimal_place).
You can use setprecision() to limit the decimal place on floating point numbers.
var = 1.0 / 3.0; // returns 0.33333333...
cout << fixed << setprecision(1) << var; // returns 0.3
This question already has answers here:
Is floating point math broken?
(31 answers)
Are all integer values perfectly represented as doubles? [duplicate]
(5 answers)
Closed 2 years ago.
I have the following snippet
cout.precision(30);
long double d = 85952643841691072928.0;
cout << d << endl;
The print statement outputs 85952643841691074560. Why are the last 4 digits before the decimal incorrect? A long double should be capable of handling a number of this size?
This question already has answers here:
How do I print a double value with full precision using cout?
(17 answers)
Closed 9 years ago.
I have a long double and I want to print all digits of it (the complete number without scientific notation) using cout .
Here's the code :-
long double d = 3456489465498484.14159265358979;
cout << "Num: " << d << endl;
output:-
Num: 3.45649e+015
While I want the output to be
Num: 3456489465498484.14159265358979;
I tried precision and set precision but the dont seem to work this way. please help
The internal representation of a floating-point value is typically binary, so initializing it requires converting from decimal to binary and displaying it requires converting from binary to decimal. Most decimal fractions do not have an exact binary representation, and most binary fractions do not have an exact decimal representation, so it is not meaningful, in general, to ask for "all" the digits. You've lost some digits on the way in, and will lose some more on the way out. Decide how many you want, and set the precision to match.
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Does setprecision in c++ round? If so why am I seeing this?
Here is the function I'm using
char* round(double value, int decimal_places)
{
decimal_places = decimal_places+1;
std::stringstream s2;
s2 << std::setprecision(decimal_places) << std::setiosflags(std::ios_base::fixed) << value;
std::string st = s2.str();
return st;
}
My input value is 0.89425 and the number of decimal palaces is 4
My output is 0.8942 but i want 0.8943 i.e., if next digit after my required decimal places is >= 5 then the output should be rounded to the next value.
0.89425 is not representable exactly in binary floating point; the nearest exactly representable value is 0.894249999999999989341858963598497211933135986328125, which is correctly rounded to decimal 0.8942.
If you want to see decimal rounding behaviour, use fixed-point or decimal floating point.
This question already has answers here:
Closed 12 years ago.
Possible Duplicate:
Prevent scientific notation in ostream when using << with double
I get 1e-1 as result after a computation how can I convert the result from exponent to dot notation i.e., 0.1 ? Why is it automatically converted to exponential notation!!
You can use the fixed I/O manipulator to force the number to be printed in fixed-point notation:
double d = 42.0;
std::cout << std::fixed << d;
(std::scientific does the opposite: it forces the number to be printed in scientific notation)
Oracle (generally) doesn't do binary numbers (some support was added in 10g).
Numbers are held in an internal format and, unless you use an implicit or explicit TO_CHAR, it is up to the "client" to display them (or any desired "prettifying").
select to_number('1e-1') num,
to_char(to_number('1e-1'),'9.9EEEE') sci_num,
to_char(to_number('1e-1')) std_num
from dual;
NUM SCI_NUM ST
--------------- --------- --
.10 1.0E-01 .1