@res = p_process(' aaaa bbbbccccccccbbb aaaaabbbbbcdddddddddddddddddddd'); print Dumper(@res); use Inline C => <<'END_OF_C_CODE'; void p_process(char *s) { char prev = 'Q'; long count = 0; long pos = 0; long i=0; AV *array; Inline_Stack_Vars; Inline_Stack_Reset; while(*s != 0) { if (count==0) { pos = i; prev = *s; count = 1; } else if (prev == *s) { count++; } else { array = newAV(); av_push(array,newSVpvn(&prev,1)); av_push(array,newSViv(pos)); av_push(array,newSViv(count)); Inline_Stack_Push(newRV_inc(array)); pos=i; prev = *s; count=1; } i++; s++; } Inline_Stack_Done; } END_OF_C_CODE