iomanip

问题 This may be a duplicate of this question, but I don't feel it was actually answered correctly. Observe: #include <iostream> #include <iomanip> using namespace std; int main () { float p = 1.00; cout << showpoint << setprecision(3) << p << endl; } Output: 1.00 Now if we change that line to: cout << fixed << showpoint << setprecision(3) << p << endl; we get: 1.000 And if we use the "opposite" of fixed we get something totally different: cout << scientific << showpoint << setprecision(3) << p <<

问题 This may be a duplicate of this question, but I don't feel it was actually answered correctly. Observe: #include <iostream> #include <iomanip> using namespace std; int main () { float p = 1.00; cout << showpoint << setprecision(3) << p << endl; } Output: 1.00 Now if we change that line to: cout << fixed << showpoint << setprecision(3) << p << endl; we get: 1.000 And if we use the "opposite" of fixed we get something totally different: cout << scientific << showpoint << setprecision(3) << p <<

问题 Say I have a command line program. Is there a way so that when I say std::cout << stuff if I don't do a std::cout << '\n' in between another std::cout << stuff , another output of stuff will overwrite the last stuff on the same line (cleaning the line) starting at the leftmost column? I think ncurses has the ability to do this? If possible, it would be great if I could say std::cout << std::overwrite << stuff Where std::overwrite is some sort of iomanip. 回答1: Have you tried carriage returns

问题 Say I have a command line program. Is there a way so that when I say std::cout << stuff if I don't do a std::cout << '\n' in between another std::cout << stuff , another output of stuff will overwrite the last stuff on the same line (cleaning the line) starting at the leftmost column? I think ncurses has the ability to do this? If possible, it would be great if I could say std::cout << std::overwrite << stuff Where std::overwrite is some sort of iomanip. 回答1: Have you tried carriage returns

问题 I don't quite understand the purpose of showpoint, i know it forces to show a decimal point, but having "cout << setprecision << fixed" is enough without the use of showpoint. Can you show me an example where showpoint is a must have? 回答1: When covering a large range of values it may be desirable to have the formatting logic to switch between the use of fixed point and scientific notation while still requiring a decimal point. If you look at the output of this example you'll see that it isn't

问题 I don't quite understand the purpose of showpoint, i know it forces to show a decimal point, but having "cout << setprecision << fixed" is enough without the use of showpoint. Can you show me an example where showpoint is a must have? 回答1: When covering a large range of values it may be desirable to have the formatting logic to switch between the use of fixed point and scientific notation while still requiring a decimal point. If you look at the output of this example you'll see that it isn't

问题 I have read several topics about the display of floating point numbers display in C++ and I couldn't find a satisfying answer. My question is: how to display all the significant digits of a floating point numbers in C++ in a scientific format (mantissa/exponent) ? The problem is that all numbers do not have the same number of significant digits in base 10. For example a double has 15 to 17 significant decimal digits precision, but std::numeric_limits<double>::digits10 returns 15 and

问题 I'm having a hard time aligning decimal values. I am pretty sure its a combination of right alignment and setprecision/fixed but it doesn't seem to be working. I know other questions have been asked on the topic but I haven't found a clear solution to getting a bunch of columns (unique cout statements to align). This is a chunk of my code: double total_collect, sales, country_tax, state_tax, total_tax; const double STATE_TAX_RATE = 0.04, COUNTRY_TAX_RATE = 0.02; // Compute taxes total_collect

问题 I'm intending to reset all output flags to default on the lines where I end using the resetiosflags function. It provides erroneous output when I attempt to do it in this manner, contrary to my expectations. #include <iostream> #include <iomanip> using namespace std; int main() { bool first; int second; long third; float fourth; float fifth; double sixth; cout << "Enter bool, int, long, float, float, and double values: "; cin >> first >> second >> third >> fourth >> fifth >> sixth; cout <<

问题 I am trying out the following C++ class for using the stream operator << to log contents from this answer: class Log { public: Log() : m_filename( "dafault.log" ) {} // if you wanna give other names eventually... Log( const std::string & p_filename ) : m_filename( p_filename ) {} virtual ~Log() { // implement your writeToFile() with std::ofstream writeToFile( m_filename, m_stream, true ); } template< typename T > Log & operator<<( const T & p_value ) { m_stream << p_value; return *this; }