Help! Why is the result "J" here?

Question

char agentName(char partner) {
return ~(partner * -1);
}
int main() {
printf("%c", agentName('K'));
}

Answer 1

According to your code
partner * -1 means:
75 * -1 = -75
-75 in binary = 11111111 10110101
Taking bitwise complement of -75
~11111111 10110101 = 00000000 01001010
Now 00000000 01001010 = 74 in ascii
Which is J's ascii value

Answer 2

mesarthim
All letters and characters we see as text have a numeric association which computers /codes use to process information.

This goes right down to binary level, -> another discussion.

K -1 = J

Answer 3

Ascii code of k is 107
107 - 1 =106
Ascci code of j is 106

Answer 4

Thanks Rushikesh

Answer 5

Thanks HK Lite

Answer 6

Thanks Rik Wittkopp

Answer 7

Because of ascii
%c print ascii values

Answer 8

Remove the dirt of code
like this
return partner -1;

Answer 9

mesarthim
Save & run this code to see what I mean.
PS: it is python, but the base principal is the same.

https://code.sololearn.com/cR8q6PcSDb0A/?ref=app

Answer 10

When you negate an integer as (k * -1) [or more simply (-k)] the result is the same as ((~k)+1). FYI, this operation is described as "taking the two's complement of k."

Observe:
If ~k + 1 = -k
Then ~k = -k - 1

Substituting -partner for k, watch what happens when we reduce ~(-partner).
~(-partner) = -(-partner) - 1
= partner - 1

So agentName() simply returns (partner -1).

If partner = 'K', then agentName() returns the next lower letter, which is 'J'.

Answer 11

Thanks Brian

Answer 12

HK Lite
Wow, my head hurts!

Great answer
😁👍