C++ Tutorial/Data Types/float output

Controlling the printing of trailing zeros and decimal points for floating-point values.

<source lang="cpp">#include <iostream>

1. include <iomanip>
2. 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;

}</source>

pad the field width with spaces and set the internal and showpos flags

<source lang="cpp">#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;

}</source>

Read and output float

<source lang="cpp">#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;

}</source>

Set and clear the showpoint flag

<source lang="cpp">#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;

}</source>

Set precision for float number output

<source lang="cpp">#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;
  }

}</source>