What does "function ?? declared implicitly" means?

Hi, I'm trying to integrate my c code to simulink.

I made a header file and a source file named file.h and file.c.

and there is a function named function1 and the code is stated below.

function1(void)
{
    static double a;
    a = a+1;
    return a;
}

Next, I made a C caller block and typed like below.

function1();

After that, I ran my code and the error is stated like this.

In line 1:error: 223, function "function1" declared implicitly

| function1();

| ^

How can I solve this error?

Answer 1

[Bruno Luong]

you need add double as return type for your function prototype and declaration

double function1(void);

double function1(void)

{

...

}

[lim daehee]

Oh, sorry, I forgot that in my question..

My code contains return type like below.

in header file
double function1();

in source file
double function1()
{
    static double a = 0;
    a = a+1;
    return a;
}

[lim daehee]

Dear Bruno Luong,

I finally found my problem.

I forgot including my c files in my simulation target..

Thanks for your help:)