C Cheatsheets

pointers.md

C pointers Cheatsheet

Increment / Decrement

Pointer action	Memory Address	Memory Contents
p	Yes, it's an address	No, this returns the address
*p	No, this dereferenced the pointer	Yes, this returns the value at that address
*p++	Incremented after value is read	Unchanged
*(p++)	Incremented after value is read	Unchanged
(*p)++	Unchanged	Incremented after it's used
*++p	Incremented before value is read	Unchanged
*(++p)	Incremented before value is read	Unchanged
++*p	Unchanged	Incremented before it's used
++(*p)	Unchanged	Incremented before it's used
p*++	Not a pointer	Not a pointer
p++*	Not a pointer	Not a pointer

Array access

Array Notation	Pointer Equivalent
array[0]	*a
array[1]	*(a+1)
array[x]	*(a+x)

printf.md

C printf Cheatsheet

%[flags][width][.precision][length]specifier

Flags

Symbol	Description
0	Left-pads numbers with 0 instead of (spaces), where padding is specified ([see width](## Width)).
-	Left-justify within the given field width; Right justification is the default ([see width](## Width)).
+	Forces numbers to be preceded by a plus or minus sign (+ or -) even for positive numbers. By default, only negative numbers are preceded with a - sign
(space)	If a number will not be preceeded by a sign, a blank space is inserted before the number.
#	Specifiers o x X: The value is preceded with 0, 0x or 0X respectively for values different than zero. Specifiers e E f: Forces the written output to contain a decimal point even if no digits would follow; By default, if no digits follow, no decimal point is written. Specifiers g G: The result is the same as with e and E but trailing zeros are not removed.

Width

Symbol	Description
(number)	Minimum number of characters to be printed - If the value is shorter than this number then it's padded with blank spaces. This does NOT truncate the value if it's longer.
*	Same as above, but instead of defining it as a fixed value in the format string, it's defined by an additional integer argument preceding the argument that will be formatted.

.precision

Symbol	Description
.number	Specifiers d i o u x X: Minimum number of digits to be written. If the value is shorter than this number then it's padded with zeroes (0). This does NOT truncate the value if it's longer. A precision of 0 means that no character is written for the value 0. Specifiers e E f: Maximum number of digits to be printed after the decimal point. Specifiers g G: Maximum number of significant digits to be printed. Specifier s: Maximum number of characters to be printed. By default all characters are printed until the ending null character is encountered. Specifier c: Ignored. When no precision is specified, the default is 1. If the period is specified without an explicit value for precision, 0 is assumed.
.*	Same as above, but instead of defining it as a fixed value in the format string, it's defined by an additional integer argument preceding the argument that will be formatted.

Length

Symbol	Description
h	Specifiers d i o u x X: The argument is interpreted as a short int or unsigned short int.
l	Specifiers d i o u x X: The argument is interpreted as a long int or unsigned long int. Specifiers c s: The argument is interpreted as a wide character or wide character string
L	Specifiers e E f g G: The argument is interpreted as a long double.

Specifier

Symbol	Description
c	Character
d or i	Signed decimal integer
e	Scientific notation using the 'e' character
E	Scientific notation using the 'E' character
f	Single or Double precision floating point
g	Uses the shorter of %e or %f
G	Uses the shorter of %E or %f
n	Nothing printed
o	Signed octal
p	Pointer address
s	Array of characters (must be null terminated or have .precision defined)
u	Unsigned decimal integer
x	Hexadecimal representation of the value
X	Hexadecimal representation of the value (capital letters)
%	prints the '%' Character