‘%d’ expects argument of type ‘int’, but argument 2 has type ‘long unsigned int’ [-Wformat=] [duplicate]

by

sizeof returns size_t you need to use %zu for the format string instead of %d. The type of unsigned integer of size_t can vary (depending on platform) and may not be long unsigned int everywhere, which is covered in the draft C99 standard section 6.5.3.4 The sizeof operator paragraph 4:

The value of the result is implementation-defined, and its type (an unsigned integer type)
is size_t, defined in (and other headers).

Also note that using the wrong format specifier for printf is undefined behavior, which is covered in section 7.19.6.1 The fprintf function, which also covers printf with respect to format specifiers says:

If a conversion specification is invalid, the behavior is undefined.248) If any argument is not the correct type for the corresponding conversion specification, the behavior is undefined.

Update

Visual Studio does not support the z format specifier:

The hh, j, z, and t length prefixes are not supported.

the correct format specifier in this case would be %Iu.

More Related Contents:

  1. C: Weird conditional printf behavior [closed]
  2. Function does not return printf
  3. Please explain the difference in the printfs below
  4. decimal of numbers in c
  5. Why do you have to link the math library in C?
  6. Why is sizeof considered an operator?
  7. Why is this happening with the sizeof operator when comparing with a negative number? [duplicate]
  8. How to link multiple implementation files in C
  9. sizeof with a type or variable
  10. What is the argument for printf that formats a long?
  11. size of character array and size of character pointer
  12. How to printf “unsigned long” in C?
  13. using printf to print out floating values
  14. How to use “zd” specifier with `printf()`?
  15. Passing too many arguments to printf
  16. printf with “%d” of numbers starting with 0 (ex “0102”) giving unexpected answer (ex ‘”66″)
  17. Wrong format specifiers in scanf (or) printf
  18. What primitive data type is time_t? [duplicate]
  19. Is it possible to print out only a certain section of a C-string, without making a separate substring?
  20. Printf long long int in C with GCC?
  21. How do I link object files in C? Fails with “Undefined symbols for architecture x86_64”
  22. What’s sizeof(size_t) on 32-bit vs the various 64-bit data models?
  23. cross-platform printing of 64-bit integers with printf
  24. What precisely does the %g printf specifier mean?
  25. Reliably determine the number of elements in an array
  26. C -> sizeof string is always 8
  27. Size of pid_t, uid_t, gid_t on Linux
  28. library not found for -lrt with QtCreator [mac os]
  29. Printf without newline in assembly
  30. In C how do I print filename of file that is redirected as input in shell

Leave a Comment