How to printf “unsigned long” in C?


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

Suppose unsigned_foo is an unsigned long, then I try:

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

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


Answers:


%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?