warning:assignment makes pointer from integer without a cast

Question

Its quite a common question but I have not got my answer so asking it again.

I have structers defined as:

struct f_lock{
              int x;
              struct f_lock *next;
     };

Then say I have a function:

struct f_lock *new_node()
{
   struct f_lock *new_f_lock;
   .....
   return new_f_lock;
}

Which I call from another function:

struct f_lock *new_f_lock;
new_f_lock = new_node(); //This line gives the error warning:assignment makes pointer from integer without a cast

Would be grateull for help Thanks

You most likely haven't declared a prototype of new_node() in scope. That being said, it's preferable you post code that people can use to reproduce your issue. — Michael F
– Michael F, Commented Jun 24, 2011 at 17:13
Shouldn't it be function f_lock *new_node() not struct f_lock *new_node()? — Swift
– Swift, Commented Jun 24, 2011 at 17:20
@Mike: in C, function is not reserved and has no special meaning. The original definition is correct. Without a typedef, the name of the type is struct f_lock; f_lock by itself is not defined — pmg
– pmg, Commented Jun 24, 2011 at 18:21
possible duplicate of Assignment makes pointer from integer without cast — jww
– jww, Commented Sep 14, 2014 at 17:55

Fred Foo · Accepted Answer · 2011-06-24 19:18:53Z

6

Did you also get the error implicit declaration of function ‘new_node’? Because in that case, you probably forgot to declare new_node in the module where you're calling it. (If you're not getting that error, recompile with -Wall to turn more warnings on.)

Explanation of the warning message: if new_node has not been declared properly, the compiler will assume it returns int, which is a kind of default return type (for historical reasons).

edited Jun 24, 2011 at 19:18

answered Jun 24, 2011 at 17:12

Fred Foo

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3 Comments

Lipika Deka Over a year ago

I din't get the error but probably that is the case. For I have noth functions in the same module

Zan Lynx Over a year ago

@Juggler: It is almost always a good idea to turn compiler warnings up to maximum.

Fred Foo Over a year ago

See also -Werror in the GCC manual, and use it to your advantage.

Dipstick · Accepted Answer · 2011-06-24 21:06:18Z

1

I seem to remember getting this (rather misleading) error message once when I had forgotten to declare a function as taking void which is required in c (but not c++) for functions with no parameters:

struct f_lock *new_node()
{
   struct f_lock *new_f_lock;
   .....
   return new_f_lock;
}

Should be:

struct f_lock *new_node(void)
{
   struct f_lock *new_f_lock;
   .....
   return new_f_lock;
}

answered Jun 24, 2011 at 21:06

Dipstick

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