What is the difference between %# and % in printf

[transgalactic]

printf ("Some different radixes: %d %x %o %#x %#o \n", 100, 100, 100, 100, 100);

%x shows 100 in hexadecimal basis

64

but %#x makes some memory address out of it

0x64what does the addition of # ?

 

[Coin]

http://en.wikipedia.org/wiki/printf

"#": Alternate form.

For 'g' and 'G', trailing zeros are not removed.

For 'f', 'F', 'e', 'E', 'g', 'G', the output always contains a decimal point.

For 'o', 'x', and 'X', a 0, 0x, and 0X, respectively, is prepended to non-zero numbers.

 

[transgalactic]

regarding this
"For 'o', 'x', and 'X', a 0, 0x, and 0X, respectively, is prepended to non-zero numbers."

X turns to hex basis and O to octal basis
i was told that when we add # it add 0X to the transformed basis number in hex basis
but in octal basis it adds 0
why??

"Used with o, x or X specifiers the value is preceeded with 0, 0x or 0X respectively for values different than zero."

for what values we have different added signs?

g is a small float number

the trail of zeros you mean
0.765000000 >>0.765

??

 

[Coin]

Prepending 0 -- like 0123 -- indeed causes a literal value to use octal basis.

Prepending 0x -- like 0x0123 -- causes a literal value to use hex basis.

As far as I know prepending x (x0123?) doesn't do anything. I could be wrong.

I assume the reason they prepend 0 in octal and 0x in hex is because in both cases they're trying to reproduce the string necessary in order to create a literal if you paste the value back into C directly.

I wouldn't worry too much about the %# badge, I don't think many people use it. I've personally actually never used it before in my life, when I want to prepend 0x I just, you know, prepend 0x...

I don't know exactly what they mean by "trailing zeroes". I'd suggest just trying it and seeing what happens if you're really curious.

for what values we have different added signs?

Don't understand the question

 

[transgalactic]

thanks i understand know