Thread: How to find ASCII value of string

Strings do not have ASCII values, individual characters do.

Converting a character to a int only gives its ASCII value if the implementation (compiler, library, host system) uses the ASCII character set. Not all implementations do.

XOR operations are performed on integral values. Strings are not integral values.

Originally Posted by shyjuu

I want to do Encryption of two Strings, so I need to find their ASCII value first and then do XOR operation on that

Look at the previous posts in this thread. Your problem description is meaningless.

If your requirement is to XOR the characters in the two strings (say the first "encrypted" character is obtained by XORing the first character from each of the two input strings), then simply XOR individual characters using a loop. But no part of that involves an act described as "getting ASCII value of a string" (there is no such operation) let alone doing an XOR "on that".

Originally Posted by shyjuu

so for XOR operation I need the decimal value so I was asking, is there any way to directly perform XOR operation on characters???

yes

Code:

    int i;
    char * str = "HELLO";
    char ch = 'A';
    for ( i = 0;str[i] != 0; ++i )
    {
      char temp = str[i] ^ ch;
      printf("%c:%02x\n",temp ,temp );
    }

Originally Posted by shyjuu

I am not able to understand the output , can u please explain, and especially the last printf statement

Characters are technically integers. He used the hex conversion character in this case ( lowercase x ), which could've also been an uppercase X depending on preference. Then, he created a string literal, and set a char variable to an 'A' for some data to initialize to. He looped through the string until the NULL termination character was reached. On each iteration, he set temporary holder value to the XOR'ed value of the constant string "HELLO" and 'A'. He then printed out the the actual encrypted character with the value in lowercase hex ( unsigned int ).

Personally I would've done the same thing this way( with the exception of using a value that varies for the XOR'ing ) :

Code:

​   
int offset; 
char * str = "HELLO";

for ( offset = 0; str[offset]; offset++ )
      printf("%c : %02X\n", (str[offset] ^ offset) , (str[offset] ^ offset) );

output shows that xoring two perfectly printable characters - you with big chance get some non-printable characters.

So after xoring you will need something like base64 encoding to get some nicely printable garbage string similar to the following

Code:

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.17 (MingW32)

iQEcBAEBAgAGBQJSGXk9AAoJEAgV1kHhjGOoYssIAMHK0RkcHRwLY4Q1Hpjj6jlH
Cl5SCDGFq+gN6m76X4PBMAUWesvDyh6kQo97VR2UjmboVa9mAQFcKj+T9jGpwe9E
PvMKv1tYFgWC+j3+uzcl0qQGpaZ5KpsvcjZgQrltkA/r0NrOm7QIe7EIIAp6Nw7x
WSv5sXUcmewzUHoijbNigd1YNTGoSgH3aVbgRW2IaBSl2Ym+tG4UQakUbu5LWpa5
Jhngwwp8AnzvkBwTi2JIiy77kNaD+cDUbo/JH6I1lsSCOfsSrIvzij4WzdWBwLO+
63PkcZuScwY8ewbF5yfPUKMpAY1BXXUtVkI6L2wIdXa2+CKppW1UBQqQqas3+uU=
=gld1
-----END PGP SIGNATURE-----