sprintf, printf and format specifiers

Question

I'm having trouble understanding what this line of code does:

    sprintf(obj, "%s.o", root);

obj and root are both character buffers, from what I read root is basically copied to obj? I'm not sure what "%so" is doing. %s is to specify a String but the .o?

thanks for any help

Answer 1

The %s will be replaced with the contents of root , and followed by the .o part of the string, which is just an "additional" text. For example, if root has "file", obj will be set to "file.o".