Thread: what does these mean?

what does these mean and what should i do when i see the following that appeared when i compile my program:

warning C206: 'usb_init': missing function-prototype
warning C206: 'usb_read': missing function-prototype
error C267: 'usb_read': requires ANSI-style prototype
warning C206: 'usb_write': missing function-prototype

you need to declare the function before running it...

for example if the function is called "sheep"

Code:

/* we declare sheep here */
void sheep();

int main()
{
     sheep();
}

/* this is where you write what sheep will do...*/
void sheep()
{
     printf("baaa...");
}

thanks a lot for that, lithium.
so does it mean if i, for example, i want to run usb_init, then i would have to put void usb_init() in front, am i right?

The prototype will depend on the function itself - you are telling the program what variable types (if any) that function needs to be passed, and what variable type it will return.

For example,

void sheep();

is the prototype for a null function returning void. If you wanted to pass a couple of strings to the function, and return an integer to mark whether the function had worked correctly, then it would be like this...

int sheep( char *string1, char *string2 );

Originally posted by cprogrammer2003
thanks a lot for that, lithium.
so does it mean if i, for example, i want to run usb_init, then i would have to put void usb_init() in front, am i right?

yes, if you are writing usb_init and it is declared as a void.

if it's already written in a library for you, then you only need to #include the library.