Multibyte character representation ASCII&Hex

Question

I'm having trouble to understand how multibyte character are represented in the ascii table : decimal format and then in hexadecimal.

For instance:

char *c = "é";
printf("%d\n%d", c[0], c[1]);

It will display :

-61

-87

In the ascii table, "é" in decimal is 130, and 82 in hex. I understand 82 is the hexadecimal value of 130, but how can we obtain 130 from -61 & -87 ?

Thanks in advance and sorry for my spelling

Answer 1

According to UTF-8 charset (used, among other, by many GNU/Linux distributions), the value of 'é' character constant is 0xC3A9, which is equivalent to 11000011 10010101 in binary. Here we can understand the results, assuming two complement representation.

• The sequence 11000011 is equal to -61 in decimal.
• The sequence 10010101 is equal to -87 in decimal.