I'm using C to read a file and assigning values from the file to parameters but the float numbers are no shown correctly when I cout the parameter value . Is the problem with the cout or with the actual value assigned to parameter? For instance, 21599.760000 is shown as 21599.8

CodePudding user response：

It's hard to be precise without some code example. For future questions it's best to share a minimal code example.

Reading from

21599.760000 is shown as 21599.8

I assume it's the default precision being defined as 1. The output precision for string conversion via std::cout can be defined with std::setprecision.

For example std::setprecision(3); will let look 1.54321 like 1.543.

CodePudding user response：

The default precision of output streams is 6 so if you haven't changed the precision then you are printing the value with 6 significant digits. You can change the precision using std::setprecision.

Note that the actual value stored in float (probably) cannot be 21599.760000 because that value is not representable as a single precision IEEE-754 floating point number. The closest representable value is 21599.759765625. In this particular case, you can get ouput with same value as the input by using precision in range [7, 16].