CODEWITHSUNDEEP
c
ankush981
ankush981

Reputation: 5417

Cast warning when working with structures

I'm revisiting C after a long time and am puzzled by a warning generated by the compiler. Here's the relevant code:

struct Unit 
{
    char str1[100];
    char str2[100];
    short expected;
};

int main()
{
    struct Unit arr[] = 
    {
        {NULL, NULL, 0},
        {NULL, "string", -1},
        {"string", NULL, 1},
        {"string", "string", 0},
        {"string1", "string2", -1},
        {"string2", "string1", 1},
        {"str", "string", -1},
        {"string", "str", 1}
    };

    printf("%d\n", arr[0].expected);
    return 0;
}

When compiled, I get:

my_strcmp.c: In function ‘main’:
my_strcmp.c:64:9: warning: initialization makes integer from pointer without a cast [enabled by default]
         {NULL, NULL, 0},
         ^
my_strcmp.c:64:9: warning: (near initialization for ‘arr[0].str1[0]’) [enabled by default]
my_strcmp.c:64:9: warning: initialization makes integer from pointer without a cast [enabled by default]
my_strcmp.c:64:9: warning: (near initialization for ‘arr[0].str1[1]’) [enabled by default]
my_strcmp.c:65:9: warning: initialization makes integer from pointer without a cast [enabled by default]
         {NULL, "string", -1},
         ^
my_strcmp.c:65:9: warning: (near initialization for ‘arr[1].str1[0]’) [enabled by default]
my_strcmp.c:65:9: warning: initialization makes integer from pointer without a cast [enabled by default]
my_strcmp.c:65:9: warning: (near initialization for ‘arr[1].str1[1]’) [enabled by default]
my_strcmp.c:66:9: warning: initialization makes integer from pointer without a cast [enabled by default]
         {"string", NULL, 1},
         ^
my_strcmp.c:66:9: warning: (near initialization for ‘arr[2].str2[0]’) [enabled by default]

I don't get it; where am I making integer from pointer? Please help.

Upvotes: 1

Views: 84

Answers (1)

Some programmer dude
Some programmer dude

Reputation: 409196

I am assuming that line 64, 65 and 66 are the ones where you initialize the structure using NULL. That will not work because NULL is a pointer, and you can't initialize an array with a pointer.

The only solution I can see is to either turn the string arrays in the structure to pointers, or to initialize the "unused" strings to the empty string "".

Upvotes: 4

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