Function Manipulator in C++

Function Manipulators in C++ are used to manipulate/modifies the input and output stream without changing the value of that variable i.e. the value that is stored in that variable will not be changed, it is just modified/formatted on the time of execution to perform the given operations like 'printing' or 'storing that modified data', etc. Function Manipulators only modifies the I/O stream using insertion(<<) and extraction(>>) operators.

There are a few Function Manipulators that are used generally:-

1. ends
   
   It is used to insert the NULL character(\0). It is defined in the ostream Header-file. It has no arguments.
   

   #include<iostream>
   int main( )
   {
   std::cout<<"Hello"<<"World!"; //O\P-1
   std::cout<<"Hello"<<std::ends<<"World!"; //O\P-2
   //either use "using namespace std" or std::
   }
   

   O/P-1-> HelloWorld!
   O/P-2-> Hello World!
   

2. endl
   
   It is used to skip a line or break a line, it works similar to '\n'. It is defined in the ostream Header-file. It has no arguments.
   

   #include<iostream>
   int main( )
   {
   std::cout<<"Hello"<<"World!"; //O\P-1
   std::cout<<"Hello"<<std::endl<<"World!"; //O\P-2
   //either use "using namespace std" or std::
   }

   O/P-1-> HelloWorld!
   O/P-2-> Hello
           World!
   

3. skipws
   
   It is used to skip the  "white spaces" in "istringstream". It is defined in the istream Header-file. It also has no arguments.
   

   #include<iostream>
   #include<sstream>
   int main( )
   {std::istringstream s("  7 92 3456");
   char a,b,c,d,e,f,g;
   s>>std::skipws>>a>>b>>c>>d>>e>>f>>g; //O\P-1
   std::cout<<a<<b<<c<<d<<e<<f<<g;
   //either use "using namespace std" or std::
   }

   O/P-1-> 7923456
   

4. setw(value)
   
   It is used to set the width between the input/output. It has an argument which defines that how much width will be provided between two consecutive outputs. It is defined in the iomanip Header-file.
   

   #include<iostream>
   #include<iomanip>
   int main( )
   {
   std::cout<<"Hello"<<"World"; //O\P-1
   std::cout<<"Hello"<<std::setw(10)<<"World!"; //O\P-2
   //either use "using namespace std" or std::
   }
   

   O/P-1-> HelloWorld!
   O/P-2-> Hello    World!
   

5. setfill(value)
   
   It is used to to fill a desired 'character' in the input/output stream. It only fills "spaces" which was created by "setw( )". It has an argument in which we can set the desired character that we want to fill-up. Its is defined in the istream Header-file.
   

   #include<iostream>
   #include<iomanip>
   int main( )
   {
   std::cout<<"Hello"<<"World"; //O\P-1
   std::cout<<"Hello"<<std::setw(10)<<std::setfill('#')<<"World"; //O\P-2
   //either use "using namespace std" or std::
   }
   

   O/P-1-> HelloWorld!
   O/P-2-> Hello#####World!
   

6. setprecision(value)
   
   It is used restricts the number of digits of floating value. It has an arguments from which we can decided the restricted value. It is defined in the iomanip Header-file.
   

   #include<iostream>
   #include<iomanip>
   int main( )
   {
   float a=18.23895; 
   std::cout<<a; //O\P-1
   std::cout<<std::setprecision(3)<<a; //O\P-2
   //either use "using namespace std" or std::
   }
   

   O/P-1-> 18.23895
   O/P-2-> 18.2
   

7. boolalpha
   
   It is used to set the boolean value '0' & '1' to "false" & "true" respectively. It has no argument and it is defined in the iostream Header-file.
   

   #include<iostream>
   int main( )
   {
   bool str1=0;
   bool str2=1;
   std::cout<<str1<<str2; //O\P-1
   std::cout<<std::boolalpha<<str1<<std::boolalpha<<str2; //O\P-2
   //either use "using namespace std" or std::
   }
   

   O/P-1-> 01
   O/P-2-> flasetrue
   

Introduction to Object-Oriented Programming language.

Introduction to C++.

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