Art of Assembly Language, 1st Edition

4.12. 4.12 Accessing the Characters Within a String

Extracting individual characters from a string is a very common and easy task. In fact, it is so easy that HLA doesn't provide any specific procedure or language syntax to accomplish this: You simply use machine instructions to accomplish this. Once you have a pointer to the string data, a simple indexed addressing mode will do the rest of the work for you.

Of course, the most important thing to keep in mind is that strings are pointers. Therefore, you cannot apply an indexed addressing mode directly to a string variable and expect to extract characters from the string. That is, if s is a string variable, then "mov( s[ebx], al );" does not fetch the character at position EBX in string s and place ...