Why do I get a warning every time I use malloc?

by

You need to add:

#include <stdlib.h>

This file includes the declaration for the built-in function malloc. If you don’t do that, the compiler thinks you want to define your own function named malloc and it warns you because:

  1. You don’t explicitly declare it and
  2. There already is a built-in function by that name which has a different signature than the one that was implicitly declared (when a function is declared implicitly, its return and argument types are assumed to be int, which isn’t compatible with the built-in malloc, which takes a size_t and returns a void*).

More Related Contents:

  1. Why does malloc initialize the values to 0 in gcc?
  2. newbie questions about malloc and sizeof
  3. Why do I get a C malloc assertion failure?
  4. aligned malloc() in GCC?
  5. Disable warning: the `gets’ function is dangerous in GCC through header files?
  6. Getting the size of a malloc only with the returned pointer
  7. Why do I get different results when I dereference a pointer after freeing it?
  8. difference between and
  9. Using sizeof() on malloc’d memory [duplicate]
  10. An alternative for the deprecated __malloc_hook functionality of glibc
  11. Implementation of sizeof operator
  12. Why does malloc allocate a different number of bytes than requested?
  13. Removing trailing newline character from fgets() input
  14. Modulo operation with negative numbers
  15. What is the meaning of lines starting with a hash sign and number like ‘# 1 “a.c”‘ in the gcc preprocessor output?
  16. What does ‘sizeof (function name)’ return?
  17. What is the difference between C, C99, ANSI C and GNU C?
  18. malloced array VS. variable-length-array [duplicate]
  19. How to access C variable for inline assembly manipulation?
  20. Detecting 64bit compile in C
  21. Do I really need malloc?
  22. Why is (sizeof(int) > -1) false? [duplicate]
  23. How to make gcc link strong symbol in static library to overwrite weak symbol?
  24. multi-word addition using the carry flag
  25. Check glibc version for a particular gcc compiler
  26. realloc(): invalid next size when reallocating to make space for strcat on char * [duplicate]
  27. How to link to a different libc file?
  28. Compiler changes printf to puts
  29. Returning struct containing array
  30. How do I compile the asm generated by GCC?

Leave a Comment