C++ Manipulator left

C++ manipulator left function is used to set the adjustfield format flag for the str stream to left.

When we set adjustfiled to left, the output is padded to the field width by inserting fill characters at the end, effectively adjusting the field to the left.

Syntax

Parameter

str: stream object whose format flag is affected.

Return value

It returns argument str.

Data Races

Data races may cause when modifies str concurrent access to the same stream object.

Exceptions

str is in a valid state, if an exception is thrown.

Example 1

Let's see the simple example to demonstrate the use of left manipulator:

#include <iostream>     // std::cout, std::internal, std::left, std::right
using namespace std;

int main () {
  int n = -24;
  cout.width(6); 
  cout << internal << n << '\n';
  
  cout.width(6); 
  cout << left << n << '\n';
  
  cout.width(6); 
  cout << right << n << '\n';
  return 0;
}

Output:

-   24
-24   
   -24

Example 2

Let's see another simple example:

#include <iostream>

int main( )
{
   using namespace std;
   double f1= 5.00;
   cout.width( 20 );
   cout << f1 << endl;
   cout << left << f1 << endl;
   return 0;
}

Output:

5
5

Example 3

Let's see another simple example:

#include <iostream>
#include <iomanip>
#include <locale>
using namespace std;

int main()
{
    cout.imbue(locale("en_US.utf8"));
    cout << "Left fill:\n" << left << setfill('*')
              << setw(12) << -1.23  << '\n'
              << setw(12) << hex << showbase << 42 << '\n'
              << setw(12) << put_money(123, true) << "\n\n";
 
    cout << "Internal fill:\n" << internal
              << setw(12) << -1.23  << '\n'
              << setw(12) << 42 << '\n'
              << setw(12) << put_money(123, true) << "\n\n";
 
    cout << "Right fill:\n" << right
              << setw(12) << -1.23  << '\n'
              << setw(12) << 42 << '\n'
              << setw(12) << put_money(123, true) << '\n';
return 0;
}

Output:

Left fill:
-1.23*******
0x2a********
USD *1.23***

Internal fill:
-*******1.23
0x********2a
USD ****1.23

Right fill:
*******-1.23
********0x2a
***USD *1.23

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