C++ printf() Function

printf() function is originally declared under the <cstdio>header file. It prints the formatted string to the standard output stdout.

Syntax: 

int printf(const char*word, .......)

Parameters:

• word: represents the string that needs to be printed on the standard output stdout,
• ……. : represents any no of extra parameters that can be passed to it.

Return Type: It returns the total number of characters written.

Example:

C++

// C++ Program to demonstrate
// use of printf()
#include <iostream>
using namespace std;

int main()
{

    char a[] = "geeksforgeeks";
    printf("The total no of characters returned by "
           "printf() is %d",
           printf("%s", a));
    return 0;
}

Output

geeksforgeeksThe total no of characters returned by printf() is 13

To know more about the return type of print() refer to return type of print() and scanf().

Example: 

C++

// C++ Program to implement
// use of % with printf()
#include <iostream>
using namespace std;

int main()
{

    int a = 5;
    printf("%d", a);
}

Output

5

Note: Anything present with the ‘%’ symbol inside printf() is termed a Format Specifiers.

Components of a Format Specifier:

• A ‘%’ sign
• width – It is an optional field that determines the width field
• Precision
• Length
• Specifier
• Flags

Flags:

It is responsible for conversion behavior between two fields. It can be classified into: 

• – :  Left Justifies the answer.
• + : attached as a sign to the beginning of the result.
• space : By default, if nothing is present space is attached to the result.
• # : alternative form of conversion
• 0 : used to pad numbers mostly trailing zeroes in integer or floating-point numbers.

Format Specifiers:

Format Specifiers are used for taking inputs and printing the output of a type.

Specifier	Output	Example
d or i	Signed decimal integer	360
u	Unsigned decimal integer	7200
o	Unsigned octal	555
x	Unsigned hexadecimal integer	7fb
e	Mantissa/Exponent notation	4.567e+8
c	Character	k
s	string of characters	geeks
%	Prints the % sign to the output screen

Note:

.x f denotes the precision of float variables up to  x decimal places

Example 1:

C++

// C++ Program to
#include <bits/stdc++.h>
using namespace std;

int main() {

   char course[]="geeksforgeeks";
  printf("Owner of this article is %s",course);
  return 0;
}

Output

Owner of this article is geeksforgeeks

Example 2:

C++

// C++ Program to demonstrate
// Use of %._f
#include <bits/stdc++.h>
using namespace std;

int main()
{
    float Self_paced_price = 3999.0,
          system_design_price = 10999.0;
    printf("the value of system design price / self paced "
           "price is %.3f",
           system_design_price / Self_paced_price);
    return 0;
}

Output

the value of system design price / self paced price is 2.750

.3f depicts the value that should be printed within 3 decimal places.

Example 3:

C++

// C++ Program implement
// Decimal to Octal
// Conversion using '%o'.
#include <bits/stdc++.h>

using namespace std;

int main()
{
    int decimal_number = 13;
    printf("Decimal to Octal conversion of %d is %o",
           decimal_number, decimal_number);
    return 0;
}

Output

Decimal to Octal conversion of 13 is 15

Example 4:

C++

// C++ Program to implement
// Decimal to hexadecimal
// Conversion using '%x'
#include <bits/stdc++.h>
using namespace std;

int main()
{
    int decimal_number = 13;
    printf("Decimal to Hexadecimal conversion of %d is %x",
           decimal_number, decimal_number);
    return 0;
}

Output

Decimal to Hexadecimal conversion of 13 is d

Example 5:

C++

// C++ Program to
// Char to int Conversion
// and Vice Versa.
#include <bits/stdc++.h>
using namespace std;

int main()
{
    int a = 78;
    printf("%c\n", a);

    int b = 'g';
    printf("%d", b);
    return 0;
}

Output

N
103