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Manipulators in C++

Last Updated : 26 Aug, 2025
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A manipulator is a special function in C++ that is used with input/output streams (like cin, cout ) to change the way data is shown or read.

We can use manipulators when we want to :

  • Format numbers
  • Set precision (decimals)
  • Align text
  • Change number base (like decimal to hexadecimal)
  • Control spacing

They are most commonly use with cout for output formatting.

Types of Manipulators

There are various types of manipulators classified on the basis type of entity they manipulate:

Output Stream Manipulators

These manipulators format how data is shown on the screen.

Manipulator

What it Does

Example Usage

endl

Inserts a newline and flushes output

cout<<"Hello"<<endl;

flush

Flushes the output buffer immediately

cout<<flush;

setw(n)

Sets width of the next output field (spaces used for padding)

cout<<setw(10)<<42;

setprecision(n)

Sets the number of digits after decimal point

cout<< setprecision(3)<<3.14159;

fixed

Uses fixed-point notation for floating numbers.

cout<<fixed<<setprecision(2)<<3.14;

scientific

Uses scientific notation (exponential)

cout<< scientific << 1234.5;

showpoint

Always shows the decimal point (even if no digits after decimal)

cout<< showpoint<< 2.0;

noshowpoint

Hides unnecessary decimal point

cout<< noshowpoint<< 2.0;

Example

C++ 
#include <iostream>
#include <iomanip>
using namespace std;

int main() {
  
    // Output a new line and flush the stream
    cout << "Hello" << endl;

    // Set width to 10 for the next output
    cout << setw(10) << 42 << endl;

    // Set precision to 3 for floating-point numbers
    cout << setprecision(3) << 3.14159 << endl;

    // Use fixed-point notation
    cout << fixed << 3.14159 << endl;

    // Use scientific notation
    cout << scientific << 3.14159 << endl;

    // Show the decimal point even for whole numbers
    cout << showpoint << 42.0;

    return 0;
}

Output
Hello
        42
3.14
3.142
3.142e+00
4.200e+01

2. Input Stream Manipulators

These manipulators help control how data is read from input streams.

Following table lists some common input stream manipulators:

Manipulator

What it Does

Example Usage

ws

Skips all leading whitespace characters (spaces, tabs, newlines) before reading input

cin>>ws>>someString;

noskipws

Stops skipping whitespace (reads every character including spaces)

cin>> noskipws >> ch;

Example

C++ 
#include <iostream>
using namespace std;

int main() {
    char c1, c2;

    // Input skips whitespace by default
    cin >> c1;  

    // Input the next character without skipping whitespace
    cin >> noskipws >> c2;  

    cout << "c1: " << c1 << ", c2: " << c2;
    return 0;
}


Input

    s    x

Output

c1: s, c2:

3. Boolean Manipulators

These manipulators control how boolean values (true/false) are displayed.

Manipulator

What it Does

Example Usage

boolalpha

Prints true or false instead of 1 or 0.

cout<< boolalpha<< true;

noboolalpha

Prints 1 or 0 instead of true/ false

cout<< noboolalpha<< true;

Example

C++ 
#include <iostream>
using namespace std;

int main() {
    bool value = true;

    // Display boolean as true/false
    cout << boolalpha << value << endl;

    // Display boolean as 1/0
    cout << noboolalpha << value;

    return 0;
}

Output
true
1

4. Alignment and Sign Manipulators

These control the alignment of output and how signs are shown.

Following table lists some common alignment and sign manipulators:

Manipulator

What it Does

Example Usage

left

Left-aligns output in the given width

cout<< left<< setw(10) << 42;

right

Right-aligns output (default for numbers)

cout<< right<< setw(10)<< 42;

internal

Places the sign to the left, padding after the sign

cout<< internal << setw(10) << -42;

showpos

Shows a + sign for positive numbers

cout << showpos << 42;

noshowpos

Hides the + sign for positive numbers

cout<< noshowpos <<42;

Example

C++ 
#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    int n = 42;

    // Align output to the left
    cout << left << setw(10) << n << endl;

    // Align output to the right
    cout << right << setw(10) << n << endl;

    // Show positive sign for numbers
    cout << showpos << n << endl;

    // Don't show positive sign for numbers
    cout << noshowpos << n;

    return 0;
}

Output
42        
        42
+42
42

5. Base Manipulators

These manipulators change the number base used for integer output.

Following table lists some common base manipulators:

Manipulator

What it Does

Example Usage

dec

Prints numbers in decimal (base 10)

cout << dec << 255;

hex

Prints numbers in hexadecimal (base 16)

cout << hex << 255;

oct

Prints numbers in octal (base 8)

cout << oct <<255;

Example

C++ 
#include <iostream>
using namespace std;

int main() {
    int n = 42;

    // Output in hexadecimal base
    cout << hex << n << endl;

    // Output in decimal base
    cout << dec << n << endl;

    // Output in octal base
    cout << oct << n;

    return 0;
}

Output
2a
42
52

Advantages of Manipulators

  • Better Control Over Output Formatting
  • Improved Readability of Output
  • Easier Boolean and Number Base display
  • Cleaner and Shorter Code

P

PulkitDahiya
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