CODEWITHSUNDEEP
objective-cstruct
skypirate
skypirate

Reputation: 673

why cannot I use struct like this?

why cannot I use struct like this? 

typedef struct { unsigned char FirstName; unsigned char LastName; unsigned int age; } User;
    User UserNick = {Nick, Watson, 24};

    NSLog(@"Your paint job is (R: %NSString, G: %NSString, B: %u)",
          UserNick.FirstName, UserNick.LastName, UserNick.age);

I mean I have used a struct like this for sure: 

typedef struct {unsigned char red; unsigned char green; unsigned char blue; } Color;
    Color carColor = {255, 65,0};

NSLog(@"Your paint job is (R: %hhu, G: %hhu, B: %hhu)",
    carColor.red, carColor.green, carColor.blue);

Upvotes: 1

Views: 92

Answers (2)

VHarisop
VHarisop

Reputation: 2826

In your definition, FirstName is an unsigned char which means it is a variable that can hold only one char as its value. However, Nick is a string, namely an array of chars.

One could do

typedef struct {
     unsigned char * FirstName;
     unsigned char * LastName;
     unsigned int age;
} User;
User Nick = {"Nick", "Watson", 24};

Upvotes: 1

rmaddy
rmaddy

Reputation: 318934

If you want to use C strings you need the following code:

typedef struct { unsigned char *FirstName; unsigned char *LastName; unsigned int age; } User;
User UserNick = {"Nick", "Watson", 24};

NSLog(@"Your paint job is (R: %s, G: %s, B: %u)",
      UserNick.FirstName, UserNick.LastName, UserNick.age);

C strings are char *. C string literals need to be in quotes. %s is the format specifier for C strings.

One other suggestion - start field names (and variables names) with lowercase letters.

And since you are working with Objective-C, you would probably end up being better off if you make User a real class instead of a struct. Then you can use properties and proper memory management. The names could be NSString instead of C strings. This makes it easy to store the objects in collections and do other useful things that are hard with a plain old struct.

Upvotes: 7

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