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std::setprecision

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setprecision
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Defined in header <iomanip>
/*unspecified*/ setprecision( int n );
Lorsqu'il est utilisé dans une expression out << setprecision(n) ou in >> setprecision(n), définit le paramètre precision du flux out ou in exactement n .
Original:
When used in an expression out << setprecision(n) or in >> setprecision(n), sets the precision parameter of the stream out or in to exactly n.
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Sommaire

[modifier] Paramètres

n -
nouvelle valeur pour la précision
Original:
new value for precision
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[modifier] Retourne la valeur

Retourne un objet de type non précisé de sorte que si str est le nom d'un flux de sortie de std::basic_ostream<CharT, Traits> type ou un flux d'entrée de std::basic_istream<CharT, Traits> type, alors l'expression str << setprecision(n) ou str >> setprecision(n) se comporte comme si le code suivant est exécuté:
Original:
Returns an object of unspecified type such that if str is the name of an output stream of type std::basic_ostream<CharT, Traits> or an input stream of type std::basic_istream<CharT, Traits>, then the expression str << setprecision(n) or str >> setprecision(n) behaves as if the following code was executed:
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str.precision(n);

[modifier] Exemple

#include <iostream>
#include <iomanip>
#include <cmath>
#include <limits>
int main()
{
    const long double pi = std::acos(-1.L);
    std::cout << "default precision (6): " << pi << '\n'
              << "std::precision(10):    " << std::setprecision(10) << pi << '\n'
              << "max precision:         "
              << std::setprecision(std::numeric_limits<long double>::digits10)
              << pi << '\n';
}

Résultat :

default precision (6): 3.14159
std::precision(10):    3.141592654
max precision:         3.14159265358979324

[modifier] Voir aussi

changements de formatage utilisés pour virgule flottante I / O
Original:
changes formatting used for floating-point I/O
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(fonction) [edit]