What is the difference between conversion specifiers %i and %d in formatted IO functions (*printf / *scanf)

c++ c printf scanf format-specifiers
Ayoub M. picture Ayoub M. · Dec 12, 2009 · Viewed 135k times · Source

What is the difference between %d and %i when used as format specifiers in printf and scanf?

Answer

Dipstick picture Dipstick · Dec 12, 2009

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.

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