Type field[edit]
The Type field can be any of:
Character
Description
%
Prints a literal % character (this type doesn't accept any flags, width, precision, length fields).
d, i
int as a signed decimal number. %d and %i are synonymous for output, but are different when used with scanf() for input (where using %i will interpret a number as hexadecimal if it's preceded by 0x, and octal if it's preceded by 0.)
u
Print decimal unsigned int.
f, F
double in normal (fixed-point) notation. f and F only differs in how the strings for an infinite number or NaN are printed (inf, infinity and nan for f, INF, INFINITY and NAN for F).
e, E
double value in standard form ([-]d.ddd e[+/-]ddd). An E conversion uses the letter E (rather than e) to introduce the exponent. The exponent always contains at least two digits; if the value is zero, the exponent is 00. In Windows, the exponent contains three digits by default, e.g. 1.5e002, but this can be altered by Microsoft-specific _set_output_format function.
g, G
double in either normal or exponential notation, whichever is more appropriate for its magnitude. g uses lower-case letters, G uses upper-case letters. This type differs slightly from fixed-point notation in that insignificant zeroes to the right of the decimal point are not included. Also, the decimal point is not included on whole numbers.
x, X
unsigned int as a hexadecimal number. x uses lower-case letters and X uses upper-case.
o
unsigned int in octal.
s
null-terminated string.
c
char (character).
p
void * (pointer to void) in an implementation-defined format.
a, A
double in hexadecimal notation, starting with 0x or 0X. a uses lower-case letters, A uses upper-case letters.[3][4] (C++11 iostreams have a hexfloat that works the same).
n
Print nothing, but writes the number of characters successfully written so far into an integer pointer parameter.
Java: indicates a platform neutral newline/carriage return.[5]
Note: This can be utilized in Uncontrolled format string exploits.
https://en.wikipedia.org/wiki/Printf_format_string