print double with precision 4 using cout [duplicate]

问题

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Closed 7 years ago.

Possible Duplicate:
Convert a double to fixed decimal point in C++

Suppose , I have double a = 0 and I want to print it as 0.0000 .

I've tried this :

cout.precision(4) ; 
cout<<a<<endl ; 

but it gaves 0 as the output.

回答1:

Just try:

#include <iomanip>
...
cout << fixed << setprecision(4);
cout << a << endl;

See here.

回答2:

#include <iomanip>
#include <iostream.h>


int main()
{
double a = 0.00;
// print a double, 2 places of precision 
cout << setprecision(4) << a << endl;
}

来源：https://stackoverflow.com/questions/13728425/print-double-with-precision-4-using-cout