％禄是格式正确无符号长。听起来有在起作用等问题在这里，如内存损坏或者未初始化的变量。也许我们展示一个较大的画面？

I can never understand how to print unsigned long datatype in C.

Suppose unsigned_boo is an unsigned long, then I try:

• printf("%lu\n", unsigned_boo)
• printf("%du\n", unsigned_boo)
• printf("%ud\n", unsigned_boo)
• printf("%ll\n", unsigned_boo)
• printf("%ld\n", unsigned_boo)
• printf("%dl\n", unsigned_boo)

And all of them print some kind of -123123123 number instead of unsigned long that I have.

%lu is the correct format for unsigned long. Sounds like there are other issues at play here, such as memory corruption or an uninitialized variable. Perhaps show us a larger picture?