table of contents
std::ios_base::precision(3) | C++ Standard Libary | std::ios_base::precision(3) |
NAME¶
std::ios_base::precision - std::ios_base::precision
Synopsis¶
streamsize precision() const; (1)
streamsize precision( streamsize new_precision ); (2)
Manages the precision (i.e. how many digits are generated) of floating point
output
performed by std::num_put::do_put.
1) Returns the current precision.
2) Sets the precision to the given one. Returns the previous precision.
The default precision, as established by std::basic_ios::init, is 6.
Parameters¶
new_precision - new precision setting
Return value¶
The precision before the call to the function
Example¶
// Run this code
#include <iostream>
int main()
{
const double d = 12.345678901234;
std::cout << "The default precision is " <<
std::cout.precision() << "\n\n";
std::cout << "With default precision d is " << d
<< '\n';
std::cout.precision(8);
std::cout << "With high precision d is " << d <<
'\n';
}
Output:¶
The default precision is 6
With default precision d is 12.3457
With high precision d is 12.345679
Defect reports
The following behavior-changing defect reports were applied retroactively to
previously published C++ standards.
DR Applied to Behavior as published Correct behavior
'precision' was defined as 'the number of digits
LWG 189 C++98 after corrected
the decimal point', but it is not correct in
some cases
See also¶
width manages field width
(public member function)
setprecision changes floating-point precision
(function)
2024.06.10 | http://cppreference.com |