Chapter 3 L7

Formatting output L7 Manipulator (flags) setprecision showpoints setleft setright setw stream

3.8 Formatting Output Can control how output displays for numeric, string data: size position number of digits Requires iomanip header file

Precision and formatted output How many values appear after and before the decimal point ?? cout<< setiosflags(ios::fixed | ios :: showpoint)<< setprecision (2); Or cout<< fixed << showpoint<< setprecision (2); Defined in the <iomanip.h> library

#include <iostream> #include <iomanip> Using namespase std; int main() { float x; cout << "x = "; cin>> x; cout << setiosflags (ios :: fixed | ios :: showpoint | ios:: left)<<setprecision(2); // or // cout << fixed << showpoint<< left <<setprecision(2); cout << x ; Return 0; } Input 1234.4567 Outout 1234.46

Stream Manipulators Used to control features of an output field Some affect just the next value displayed: setw(x): print in a field at least x spaces wide. Use more spaces if field is not wide enough Some affect values until changed again: fixed: use decimal notation for floating-point values setprecision(x): when used with fixed, prints floating-point value using x digits after the decimal. Without fixed, prints floating-point value using x significant digits // show an example of both Mix18.cpp showpoint: always print decimal for floating-point values )

Manipulator Examples const double e = 2.718; cout << setw(8) << e; // 2.718 in a // field 8 wide cout << setprecision(2); cout << e; // 2.7 cout << fixed<<setprecision(2); cout << e; // 2.72 double price = 25.0, discount = 0.6; cout << fixed << setprecision(2); cout << price * discount; // 15.00

Formatting output stream manipulator setw() int Numb1 = 100, Numb2 = 200, Numb3 = 300; cout << Numb1 <<Numb2 <<Numb3; Gives us 100200300 BUT: cout << setw(5 )<<Numb1<<setw(7) << Numb2<<setw(5)<<Numb3 SS100SSSS200SS300 100 200 300

The left and right Manipulators “right is the default” float Miles = 134.567; cout << setw(12)<<Miles; SSSSS134.567 cout << setiosflags (ios::left) <<setw(12) << Miles; cout<<left<<setw(12)<<Miles; 134.567SSSSS cout << setiosflags(ios::right) << setw(12) << Miles;

Formatting output setprecision manipulator setprecision() float Num1 = 2100.123456; cout << Num1; 2100.123456 cout << fixed<<setprecision(4)<<Num1; 2100.1235 cout << fixed<<setprecision(5)<<Num1; 2100.12346 cout <<fixed<<setprecision(6)<<Num1;

BIG difference between set precision in Turbo and .net compilers Look at table 3-11 page 109 Compare with the outcome of this program. #include<iostream.h> #include<iomanip.h> int main() { float Num1 = 28.92786; cout<< setiosflags(ios::fixed)<< setprecision (3) << Num1; return 0; } Output 28.928 on turbo and DEV, 28.9 on dot net !!

Formatting output setprecision manipulator setprecision() float Num1 = 2100.123456; cout << setprecision(2)<<Num1; 2.1e+03 cout << setprecision(12)<<Num1; 2100.12345688 !!!!

Formatting output manipulator setprecision + fixed() Forces cout to print the digits in fixed point notation or decimal. float Num1 = 210.123456; cout<< setiosflags(ios::fixed)<< setprecision (2) << Num1; 210.12 cout<< setiosflags(ios::fixed)<< setprecision (4) << Num1; 210.1234

Formatting output manipulator showpoint() Forces cout to display the trailing zeros. float Num1 = 210.0000 ; cout << Num1; 210 cout<< setiosflags(ios :: showpoint)<< Num1; 210.0000 NOTE: Cout <<setprecision(2)<<showpoint; // works for .net AND FOR DEV but not for Turbo

showpoint and setprecision float Num1 = 210.0000 ; cout<< setprecision(6)<< Num1; 210 // would not show the 0000 cout setsettiosflags (ios::showpoint) <<setprecision(6)<< Num1; 210.000000

showpoint and setprecision causes the decimal points and trailing zeros to be displayed EVEN if there is no fractional part float Num1 = 210 ; cout<< setiosflags(ios :: showpoint) << setprecision(6) << Num1; 210.000000

The fill( ) function cout.fill (‘x’) Changes the fill character, whicjh is by default a space to be something else, ie x. float Miles = 134.567; cout << setiosflags(ios :: right) << setw(12) << Miles; SSSSS134.567 cout.fill('x'); cout << setiosflags(ios :: right) << setw(12) <<Miles; xxxxx134.567

setw() and strings cout<<“I Love C++ Programming”; Will give you: I Love C++ Programming cout<<setw(22)<<“I Love C++ Programming”; Would give you the same, as long as its 22, or less. cout<<setw(30)<<“I Love C++ Programming”; SSSSSSSSI Love C++ Programming // right justified

When the size of the setw() less or = the size of the string // This program demonstrates the setw manipulator being // used with values of various data types. #include <iostream> #include <iomanip> using namespace std; int main() { int intValue = 3928; double doubleValue = 91.5; const int ARRAY_SIZE = 14; char cStringValue[ARRAY_SIZE] = "John J. Smith"; cout << "(" << setw(5) << intValue << ")" << endl; cout << "(" << setw(8) << doubleValue << ")" << endl; cout << "(" << setw(16) << cStringValue << ")" << endl; // cout << "(" << setw(16) << cStringValue << ")" << endl system("pause"); return 0; }

Program example// notice the changes from yours // we will run this program to demonstrate how flags work // if statments and loops wil be covered soon #include <iostream> #include <iomanip> using namespace std; int main() { float weight; int i; for (i = 0; i < 6; i++) cout<< fixed << showpoint<< setprecision (2); //cout<< setiosflags(ios :: fixed |ios :: showpoint)<< setprecision (2); cout << " \n enter weight \n" ; cin >> weight; if (weight > 150 ) cout << weight << setw(3)<< " over weight "; else if (weight > 100 && weight < 150) cout<< weight<<setw(3) << " no risk "; else cout << weight<<setw(3)<<" too thin "; } return 0;