Format specifiers define how printf() and scanf() interpret the corresponding arguments. The specifier must match the type of the value being printed or the object receiving input.

#include <stdio.h>

int main()
{
    int number = 25;
    float temperature = 36.5f;
    double value = 3.14159;
    char letter = 'A';

    printf("Integer   : %d\n", number);
    printf("Float     : %f\n", temperature);
    printf("Double    : %f\n", value);
    printf("Character : %c\n", letter);

    return 0;
}

Example Output #

Integer   : 25
Float     : 36.500000
Double    : 3.141590
Character : A

Explanation #

The format string contains conversion specifications such as:

%d
%f
%c

Each specification determines how the corresponding argument is formatted.

For example:

printf("%d\n", number);

uses %d for an int.

printf("%c\n", letter);

uses %c for a character.

Common printf() Format Specifiers #

For printf(), float arguments are promoted to double, so %f is used for both float and double values.

For scanf(), the corresponding format requirements are different. For example, %f expects a float *, while %lf expects a double *. These differences are covered in the dedicated scanf() lessons.