Материал из C\C++ эксперт
Controlling the printing of trailing zeros and decimal points for floating-point values.
#include <iostream>
#include <iomanip>
#include <cmath>
using std::cout;
using std::endl;
using std::ios;
int main()
{
cout << "Before setting the ios::showpoint flag\n"
<< "9.9900 prints as: " << 9.9900
<< "\n9.9000 prints as: " << 9.9000
<< "\n9.0000 prints as: " << 9.0000
<< "\n\nAfter setting the ios::showpoint flag\n";
cout.setf( ios::showpoint );
cout << "9.9900 prints as: " << 9.9900
<< "\n9.9000 prints as: " << 9.9000
<< "\n9.0000 prints as: " << 9.0000 << endl;
return 0;
}pad the field width with spaces and set the internal and showpos flags
#include <iostream>
using namespace std;
int main()
{
cout << "Hello" << endl;
cout.width(12);
cout.fill(" ");
cout.setf(ios::showpos | ios::internal);
cout << 765.34 << endl;
return 0;
}Read and output float
#include <iostream>
using namespace std;
int main()
{
int myInt;
long myLong;
double myDouble;
float myFloat;
unsigned int myUnsigned;
char myWord[50];
cout << "int: ";
cin >> myInt;
cout << "Long: ";
cin >> myLong;
cout << "Double: ";
cin >> myDouble;
cout << "Float: ";
cin >> myFloat;
cout << "Word: ";
cin >> myWord;
cout << "Unsigned: ";
cin >> myUnsigned;
cout << "\n\nInt:\t" << myInt << endl;
cout << "Long:\t" << myLong << endl;
cout << "Double:\t" << myDouble << endl;
cout << "Float:\t" << myFloat << endl;
cout << "Word: \t" << myWord << endl;
cout << "Unsigned:\t" << myUnsigned << endl;
cout << "\n\nInt, Long, Double, Float, Word, Unsigned: ";
cin >> myInt >> myLong >> myDouble;
cin >> myFloat >> myWord >> myUnsigned;
cout << "\n\nInt:\t" << myInt << endl;
cout << "Long:\t" << myLong << endl;
cout << "Double:\t" << myDouble << endl;
cout << "Float:\t" << myFloat << endl;
cout << "Word: \t" << myWord << endl;
cout << "Unsigned:\t" << myUnsigned << endl;
return 0;
}Set and clear the showpoint flag
#include <iostream>
using namespace std;
int main()
{
int x = 100;
double f = 98.6;
double f2 = 123456.0;
double f3 = 1234567.0;
// Set the showpoint flag.
cout << "Setting showpoint flag.\n";
cout.setf(ios::showpoint);
cout << "f2 with showpoint set: " << f2 << "\n\n";
cout << "Clearing the showpoint flag.\n\n";
cout.unsetf(ios::showpoint);
return 0;
}Set precision for float number output
#include <iostream>
using namespace std;
int main(void)
{
int i;
float value = 1.2345;
for (i = 0; i < 4; i++){
cout.precision(i);
cout << value << endl;
}
}
