In this blog post, we will provide a helpful reference for all the C conversion specifiers commonly used with functions like printf()
, scanf()
, and other I/O functions.
Specifier | Meaning |
---|---|
%d / %i |
Signed decimal integer |
%u |
Unsigned decimal integer |
%c |
Unsigned char |
%s |
String |
%p |
Pointer in hexadecimal form |
%o |
Unsigned octal integer |
%x / %X |
Unsigned hexadecimal number |
%e |
Floating point number in exponential format in e notation |
%E |
Floating point number in exponential format in E notation |
%f |
double number in decimal format |
%g / %G |
double number in decimal format or exponential format, depending on the value |
In addition to these specifiers, we have a set of modifiers.
Let’s start with the use of digits as modifiers. By using a digit between %
and the format specifier, you can specify the minimum field width. For example, %3d
will take up 3 spaces regardless of the number being printed.
The following code:
printf("%4d\n", 1);
printf("%4d\n", 12);
printf("%4d\n", 123);
printf("%4d\n", 1234);
will produce the following output:
1
12
123
1234
If you put a dot before the digit, you are indicating the precision, which is the number of decimal digits. This applies to decimal numbers. For example:
printf("%4.2f\n", 1.0);
printf("%4.3e\n", 12.232432442);
printf("%4.1e\n", 12.232432442);
printf("%4.1f\n", 123.22);
will print:
1.00
1.223e+01
1.2e+01
123.2
In addition to digits, we also have three special letters: h
, l
, and L
.
h
, when used with integer numbers, indicates ashort int
(e.g.,%hd
) or ashort unsigned int
(e.g.,%hu
).l
, when used with integer numbers, indicates along int
(e.g.,%ld
) or along unsigned int
(e.g.,%lu
).L
, when used with floating point numbers, indicates along double
(e.g.,%Lf
).