Tell HN: C Experts Panel – Ask us anything about C

Re:Tell HN: C Experts Panel – Ask us anything about C by gbear605 on Tuesday April 14, 2020 @12:41PM (#22868116)

Declaring it with a custom struct:

    int raw_arr[4] = {0,0,0,0};
    struct SmartArray arr;
    arr.length = 4;
    arr.val = raw_arr;
    some_function(arr);

Smart declaration with custom type: (assume that they'll come up with a good syntax)

    smart_int_arr arr[4] = {0,0,0,0};
    some_function(arr);

With the custom struct, it requires the number `4` to be typed twice manually, while in the second it only needs a single input.

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Re:Tell HN: C Experts Panel – Ask us anything about C by fkeeal on Wednesday April 15, 2020 @06:35PM (#22883930)

You actually never need to specify the size explicitly in C.

Here are some other ways to declare your struct without needing as much boiler plate per declaration.

    #define MAKE_SMARTARRAY(_smartarr, _array) \
            do {\
                _smartarr.val = (_array);\
                _smartarr.len = sizeof((_array))/sizeof((_array[0]));\
            }while(0)
    
    struct SmartArray
    {
        int *val;
        int len;
    };
    
    int main()
    {
        int array[] = {0,0,0,0};
        
        struct SmartArray arr = {.val = array, 
                                    .len = sizeof(array)/sizeof(array[0])};
        struct SmartArray arr2;
        struct SmartArray arr3;
        
        MAKE_SMARTARRAY(arr2, ((int[]){5,6,7,8}));
        MAKE_SMARTARRAY(arr3, array);
    
        return 0;
    }

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