How C + + cout preserves fractional output

Reference: http://upliu.net/how-cout-out-2-precision.html

We all know that the printf () function in C can be very handy for keeping several decimal outputs

However, in C + + you can also control fractional retention, cout () and printf () or some differences

Cout<<setiosflags (ios::fixed) <<setprecision (2);//requires header file # include <iomanip>

　　

Then output the real type variable that can retain 2 decimal places output, of course you want to keep three decimal places, Setprecision (3) on the line.

Setprecision refers to setting the output precision when there is no

Cout<<setiosflags (ios::fixed)

, the output format is a valid number of digits for the data, such as

2float a = 123.666;cout<<setprecision (5) <<a;

Will output 123.67 (note here that it will be rounded up). If the parameters in the setprecision are less than the integer digits, they will be output in exponential form, for example

2float a = 123.666;cout<<setprecision (2) <<a;

　　

Will output 1.2e+002.

Setiosflags (ios::fixed) refers to a fixed floating-point display that retains n-bit output when setiosflags (ios::fixed) and Serprecision (n) two.

It is also important to note that each output is set only once, because the two scopes are subsequent objects, not just the latter.

How C + + cout preserves fractional output