what If i store 025 value to int

Question

Int i =025;
Cout<<i;

Then why output of this code is 21?

Answer 1

Because any integer value starting with zero is treated as octal literal.
and on translation from octal 25 to decimal, we get
25 = 2×8^1 + 5×8^0
= 2×8 + 5×1
= 16 + 5
= 21

Answer 2

Thanx devender.. But why octal? Also is there any other conventions like this

Answer 3

Because it's also a very good thing to convert a decimal into octal without even writing the code for it

Answer 4

yes it is interesting
when u start assigning integers with 0 it expects a octal number. just like when u start with '0x' the compiler expects a hexadecimal number.
you can try ro assign 078 but it will show an error as '8' is not a valid octal input. it will take 0 to 7 as input. same you can try to input 0xa7 to see if it takes and it will take it as a hexadecimal number.