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missing braces around initializer warning

I couldn't find an anser on google...The following code is a tiny made-up example showing the problem I am looking at, at work.

I have a struct:
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  1. struct door_t {
  2.   BOOL color;
  3.   BOOL size;
  4.   char    name[4];
  5.   char    keys[10];
  6. }
  7.  
  8. struct door_t knobs = { 
  9. 0, //color
  10. 0, //size
  11. "", //name[0]
  12. "", //name[1]
  13. "", //name[2]
  14. "", //name[3]
  15. "" //keys[100]
  16. };
  17.  
The warnings are:
warning: missing braces around initializer
warning: (near initialization for 'knobs.name')
warning: missing initializer
warning: (near initialization for 'knobs.keys')

Can someone look at this with me and explain what the missing braces are please?
Nov 25 '08 #1
9 18390
boxfish
469 Expert 256MB
You need a semicolon after the declaration of your struct.
Hope this helps.
Edit:
I see that was probably not what was causing the problem.
The way you are initializing name is just wrong. You can initialize it to four spaces, like this:
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  1. struct door_t knobs = {
  2. 0,
  3. 0,
  4. "    ",
  5. "",
  6. };
or four nulls:
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  1. struct door_t knobs = {
  2. 0,
  3. 0,
  4. "\0\0\0\0",
  5. "",
  6. };
and you can do it like this:
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  1. struct door_t knobs = {
  2. 0,
  3. 0,
  4. {' ', ' ', ' ', ' '},
  5. "",
  6. };
But you can't initialize it like four separate members of the struct, and you can't initialize it with four strings, and you can't initialize it with empty characters.
Hope this helps.
Nov 26 '08 #2
UPDATED CODE:

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  1.  struct door_t {
  2.    BOOL color;
  3.    BOOL size;
  4.    char    name[4];
  5.    char    keys[10];
  6.  };
  7.  
  8.  struct door_t knobs = { 
  9.  0, //color
  10.  0, //size
  11.  "", //name[0]
  12.  "", //name[1]
  13.  "", //name[2]
  14.  "", //name[3]
  15.  "" //keys[100]
  16.  };
  17.  
Nov 26 '08 #3
boxfish
469 Expert 256MB
Sorry about the incorrect diagnosis of your problem. I hope my edit clears things up.
Nov 26 '08 #4
@boxfish
Thank you for your help - I didn't know that at all...
Nov 26 '08 #5
or four nulls:
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  1. struct door_t knobs = {
  2. 0,
  3. 0,
  4. "\0\0\0\0",
  5. "",
  6. };
Hi - I went with four nulls....but I kept getting the "missing braces" warning until I did this:
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  1. {"\0\0\0\0"},
  2.  
It shut the compiler warning up but is that combination of characters okay?

Thanks!
Nov 26 '08 #6
boxfish
469 Expert 256MB
I'm not sure why the braces shut up the compiler. Try three nulls instead of four, because like any other string, this one will get a null tacked on the end; my bad. Anyway, to fill up your string with nulls, you can just use an empty string, "", and I'm pretty sure that will initialize it to nulls. And if you do it like this:
{'\0', '\0', '\0', '\0'}
it won't add the extra null.
Hope this helps.
Edit:
I have a faster keyboard, Banfa. :-p
Nov 26 '08 #7
Banfa
9,064 Expert Mod 8TB
I suspect the problem is that "\0\0\0\0" is an array of 5 characters (remember the implicit /0 added by the compiler at the end of the string) but name is only 4 characters long.

Not providing enough data is rarely a problem (the compiler just fills in with 0) but providing too much leaves the compiler wondering what you were talking about.

If name is a string then simply initialise it to "" an empty string. On the other hand it name is an array of 4 characters then initialise it with {'\0', '\0', '\0', '\0'} and on the other hand if name is actually an array of 4 numbers (in the range of a char) then initialise it with {0, 0, 0, 0}.
Nov 26 '08 #8
@Banfa

OH!!!!!!!!!!!! I just realized that the name array looks like this in the code:
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  1. char nameVal[MAX_VAL] [40];
  2.  

So it only goes away if I have the brackets:
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  1.  {""},
  2.  
but I don't know much about multi-dimension arrays in C... but it makes the struct initialization behave differently. Why is this?!?!? I would love to know.
Thanks!
Nov 26 '08 #9
donbock
2,422 Expert 2GB
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  1. char nameVal[MAX_VAL] [40];
  2.  
  3. /* Is equivalent to ... */
  4. typedef char NameString[40];
  5. NameString nameVal[MAX_VAL];
  6.  
That is, nameVal is an array of MAX_VAL buffers, each of which is 40 chars long.

In your initializer '{""}', the braces enclose the initializers for the MAX_VAL NameStrings. The double quotes enclose the initializer for the first NameString in the array. No initializers are provided for the remaining MAX_VAL-1 NameStrings.

Check what happens if you take out the double quotes, so the initializer is simply '{}'. I think that's legal. The result is an empty initializer (which defaults to initial value of all zeroes) that you need as a placeholder if there are initializers for subsequent fields in the structure.

I generally avoid multidimensional arrays because they almost always engender some level of confusion on the programming team. Worse, the people who are most confused are commonly unaware of it.
Nov 26 '08 #10

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