C++ std::setprecision in C# -

i'm picking c# porting legacy c++ code , keep output identical. used along lines of

output << std::setprecision(10) << (double) value; 

i figured be

output.write("{0:f10}", value); 

but didn't trick. values > 1 more digits. common online suggestion math.round first, appends zeroes if total length < 10.

so put together:

    // std::setprecision not same ":f10", mirror original behavior     static string setprecision(double value) {         string ret = value.tostring();          // don't substring(0, 11), need apply rounding,         // , don't this, don't want append zeroes,         // 10 digits + period, 0.. not counting total         if(ret.length > digits + 1)             ret = math.round(value, digits + (value < 1 ? 1 : 0) - ret.indexof('.')).tostring();          return ret;     } 

where digits static constant; make variable, project in particular makes little sense so.

still, seems overly complicated. there more elegant way traditional behavior?

as requested example i/o

// c++ double test = 0; out << std::setprecision(10); test = 0.123456780;   out << test << '\n'; test = 0.0123456781;  out << test << '\n'; test = 0.11234567819; out << test << '\n'; test = 1.00234567899; out << test << '\n';  // c# double test = 0;             test = 0.123456780;   output.writeline(setprecision(test)); test = 0.0123456781;   output.writeline(setprecision(test)); test = 0.11234567819; output.writeline(setprecision(test)); test = 1.00234567899; output.writeline(setprecision(test)); 

both produce:

0.12345678 0.0123456781 0.1123456782 1.002345679 

and meanwhile noticed heading zeroes don't seem count towards total rather first;

// c++ test = 0.012345678906;    out << test << '\n'; // 0.01234567891 test = 0.0012345678906;   out << test << '\n'; // 0.001234567891 test = 0.00012345678906;  out << test << '\n'; // 0.0001234567891  // c# test = 0.012345678906;   output.writeline(setprecision(test)); // 0.0123456789 test = 0.0012345678906;  output.writeline(setprecision(test)); // 0.0012345679 test = 0.00012345678906; output.writeline(setprecision(test)); // 0.0001234568 

i'll have correct if there isn't more straightforward solution.

it sounds want print number specific number of significant digits. can use g format string specify number of digits use.

output.write("{0:g10}", value);