C++/Data Type/float output
Содержание
- 1 Change cout width and precision for string and float number output
- 2 Controlling precision of floating-point values
- 3 Floating-point values in system default, scientific, and fixed formats.
- 4 Output float in default floating-point format
- 5 Output float number with fixed flag
- 6 Output float type number with scientific format
- 7 Set precision for float number
Change cout width and precision for string and float number output
#include <iostream>
using namespace std;
int main(void)
{
cout.precision(4);
cout.width(10);
cout << 10.12345 << endl;
cout.width(10);
cout.fill("-");
cout << 10.12345 << endl;
cout.width(10);
cout << "Hi!" << endl;
cout.width(10);
cout.setf(ios::left);
cout << 10.12345;
}
Controlling precision of floating-point values
#include <iostream>
#include <iomanip>
using std::cout;
using std::cin;
using std::endl;
using std::ios;
using std::setiosflags;
using std::setprecision;
#include <cmath>
int main()
{
double root2 = sqrt( 2.0 );
int places;
cout << setiosflags( ios::fixed) << endl;
for ( places = 0; places <= 9; places++ ) {
cout.precision( places );
cout << root2 << "\n";
}
for ( places = 0; places <= 9; places++ )
cout << setprecision( places ) << root2 << "\n";
return 0;
}
Floating-point values in system default, scientific, and fixed formats.
#include <iostream>
using std::cout;
using std::endl;
using std::ios;
int main()
{
double x = .001234567, y = 1.946e9;
cout << "Displayed in default format:\n" << x << "\t" << y << "\n";
cout.setf( ios::scientific, ios::floatfield );
cout << "Displayed in scientific format:\n" << x << "\t" << y << "\n";
cout.unsetf( ios::scientific );
cout << "Displayed in default format after unsetf:\n" << x << "\t" << y << "\n";
cout.setf( ios::fixed, ios::floatfield );
cout << "Displayed in fixed format:\n"<< x << "\t" << y << endl;
return 0;
}
Output float in default floating-point format
#include <iostream>
using namespace std;
int main()
{
int x = 100;
double f = 98.6;
double f2 = 123456.0;
double f3 = 1234567.0;
cout << "f, f2, and f3 in default floating-point format:\n";
cout << "f: " << f << " f2: " << f2 << " f3: " << f3 << endl;
return 0;
}
Output float number with fixed flag
#include <iostream>
#include <iomanip>
using namespace std;
int main(void){
float value = 0.000123;
cout << setiosflags(ios::fixed) << value << "\n";
}
Output float type number with scientific format
#include <iostream>
#include <iomanip>
using namespace std;
int main(void){
float value = 0.000123;
cout << setiosflags(ios::scientific) << value << "\n";
}
Set precision for float number
#include <iostream>
#include <iomanip>
using namespace std;
int main(void){
int i;
float value = 1.2345;
for (i = 0; i < 4; i++)
cout << setprecision(i) << value << "\n";
}