freeCodeCamp/guide/english/c/format-specifiers/index.md

title
Format Specifiers

Format Specifiers

Format specifiers defines the type of data to be printed on standard output. Whether to print formatted output or to take formatted input we need format specifiers. Format specifiers are also called as format string.Format specifier is used during input and output. It is a way to tell the compiler what type of data is in a variable during taking input using scanf() or printing using printf(). Some examples are %c, %d, %f, etc.

Character format specifier : %c

#include <stdio.h> int main() { char ch = 'A'; printf("%c\n", ch); return 0; }

Output: A

Integer format specifier : %d, %i

#include <stdio.h> int main() { int x = 45, y = 90; printf("%d\n", x); printf("%i\n", x); return 0; }

Output: 45 45

Double format specifier : %f, %e or %E

#include <stdio.h> int main() { float a = 12.67; printf("%f\n", a); printf("%e\n", a); return 0; }

Output: 12.670000 1.267000e+01

Unsigned Octal number for integer : %o

#include <stdio.h> int main() { int a = 67; printf("%o\n", a); return 0; }

Output: 103

Unsigned Hexadecimal for integer : %x, %X

#include <stdio.h> int main() { int a = 15; printf("%x\n", a); return 0; }

Output: f

String printing : %s

#include <stdio.h> int main() { char a[] = "nitesh"; printf("%s\n", a); return 0; }

Output: nitesh

---

scanf(char *format, arg1, arg2, …)

decimal integer : %d

#include <stdio.h> int main() { int a = 0; scanf("%d", &a); // input is 45 printf("%d\n", a); return 0; }

output: 45

Integer may be octal or in hexadecimal : %i

#include <stdio.h> int main() { int a = 0; scanf("%i", &a); // input is 017 (octal of 15 ) printf("%d\n", a); scanf("%i", &a); // input is 0xf (hexadecimal of 15 ) printf("%d\n", a); return 0; }

output: 15 15

Floating data type : %f, %e(double), %lf(long double)

#include <stdio.h> int main() { float a = 0.0; scanf("%f", &a); // input is 45.65 printf("%f\n", a); return 0; }

Output: 0.000000

String input : %s

#include <stdio.h> int main() { char str[20]; scanf("%s", str); // input is nitesh printf("%s\n", str); return 0; }

Output: nitesh

Character input : %c

#include <stdio.h> int main() { char ch; scanf("%c", &ch); // input is A printf("%c\n", ch); return 0; }

output: A

The % specifiers that you can use in ANSI C are:

Specifier	Used For
%c	a single character
%s	a string
%hi	short(signed)
%hu	short(unsigned)
%Lf	long double
%n	prints nothing
%d	a decimal integer
%o	an octal (base 8) integer
%x	a hexadecimal (base 16) integer
%p	an address (or pointer)
%f	a floating point number for floats
%u	int unsigned decimal
%e	a floating point number in scientific notation
%E	a floating point number in scientific notation
%%	The % symbol!