I know it is string interpolation, but I can't understand what is the exact meaning. It seems it convert int2 to hexadecimal as a string(I see this behavior in debugging) but what is the int1 role? (I guess it is the size of hexadecimal) can anybody explain in detail?
* means to get the field width from the corresponding argument, rather than hard-coding it into the format string (e.g. %08x means to print 8 hex digits). So int1 specifies the number of digits to print.
The 0 before the field width means to pad the output with zeroes rather than spaces.