在这种情况下如何正确使用struct

Question

I am new to programming in C and I am trying to figure out the correct use of the struct, as an example:

int main (int argc, char *argv[])
{
    char player_one = "bob";
    char player_two = "steve";

    enum colour
    {
        P_RED, P_WHITE
    };

    struct player
    {
        char name[MAX_NAME_LEN+1];
        enum colour col;
    };

    int rndNumber;
    srand (time(NULL));
    rndNumber = rand() % 2;
    struct player p1 = {player_one, rndNumber};
    struct player p2 = {player_two, rndNumber};

    printf("%s\n", p1.name);
    printf("%d\n", p1.col);
    printf("%s\n", p2.name);
    printf("%d\n", p2.col);
    return EXIT_SUCCESS;
}

when I try to compile this code I get several errors.

warning: initialization makes integer from pointer without a cast [enabled by default]
char player_one = "bob";

warning: missing braces around initializer [-Wmissing-braces]
struct player p1 = {player_one, rndNumber};

warning: (near initialization for ‘p1.name’) [-Wmissing-braces]

warning: initializer element is not computable at load time [enabled by default]

warning: ISO C90 forbids mixed declarations and code [-Wpedantic]
struct player p1 = {player_one, rndNumber};

which are making it so that p1.name and p2.name print nothing and p1.col and p2.col always print 0 even though rndNumber successfully prints random numbers. So what am I doing wrong here? oO

Answer 1

In C, strings are not characters, but arrays of characters. So declare them like this:

char *player_one = "bob";

or

char player_one[] = "bob";

Secondly, in the structure you can either declare the string as:

char name[MAX_NAME_LEN+1];

or

char *name;

The difference is that in the first case, MAX_NAME_LEN+1 characters are allocated, in the second case name is just a pointer. So in the first case, you need to copy stings:

strcpy(p1.name, player_one);

in the second case, assignment will do:

p1.name = player_one;

or as you have done it:

p1 = {player_one, rndNumber};

Answer 2

First of all, define the new types outside the main() function:

#define MAX_NAME_LEN 100


typedef enum
{
    RED, WHITE
} Color;


typedef struct
{
    char *name;
    Color color;
} Player;

Then, in the main() function, you can use the new types like this:

char *player_one = "bob";
char *player_two = "steve";

Color redColor = RED;
Color whiteColor2 = WHITE;

Player p1 = { player_one, redColor };
Player p2 = { player_two, whiteColor2 };

printf("%s\n", p1.name);
printf("%d\n", p1.color);
printf("%s\n", p2.name);
printf("%d\n", p2.color);

p1.name = "john";
p2.color = RED;

printf("%s\n", p1.name);
printf("%d\n", p1.color);
printf("%s\n", p2.name);
printf("%d\n", p2.color);