C

%d and %i

[0]
Format Specifier %d
The format specifier %d takes integer value as a signed decimal integer value
which means values should be decimal whether it is negative or positive.

Format Specifier %i
The format specifier %i takes integer value as an integer value which means 
values should be decimal, octal and hexadecimal and octal value is provided by
preceding ‘0’ while hexadecimal value is provided by preceding ‘0x’.

[1]
They are the same when used for output, e.g. with printf.

However, these are different when used as input specifier e.g. with scanf, 
where %d scans an integer as a signed decimal number, but %i defaults to 
decimal but also allows hexadecimal (if preceded by 0x) and octal (if preceded
by 0).

So 033 would be 27 with %i but 33 with %d.

[2]
These are identical for printf but different for scanf. For printf, both %d 
and %i designate a signed decimal integer. For scanf, %d and %i also means a 
signed integer but %i inteprets the input as a hexadecimal number if preceded
by 0x and octal if preceded by 0 and otherwise interprets the input as 
decimal.

%d and %i

•%d and %i behave similar with printf

There is no difference between the %i and %d format specifiers for printf. 

•%d and %i behavior is different in scanf

%d assume base 10 while %i auto detects the base. Therefore, both specifiers 
behaves differently while they are used with an input specifier. So, 012 would 
be 10 with %i but 12 with %d. 

%d takes integer value as signed decimal integer i.e. it takes negative values
along with positive values but values should be in decimal otherwise it will 
print garbage value.( Note: if input is in octal format like:012 then %d will 
ignore 0 and take input as 12) 
 
%i takes integer value as integer value with decimal, hexadecimal or octal type.

To enter a value in hexadecimal format – value should be provided by preceding
“0x” and value in octal format – value should be provided by preceding “0”.