AVR-Chat

i would like to get the sum of values of characters in a string. I 
use to get the checksum.

ex.
strcopy(string1, "abcdefghigklmnopqrstuvwxyz");

this does not work:

sum=0;
for (i = 0; i < strlen(string1); i++)
{
sum = sum + string[i];
}

but this works:

sum = string1[0] + string1[1] + .... + string[25];

but is too lengthy to do the later method.
is there any shorter method to get the sum of values in a string? 

regards

mago