CODEWITHSUNDEEP
cpointersstruct
Gautam
Gautam

Reputation: 7958

C : Working with structures and pointers , error : invalid type argument of unary ‘*’

I'm working on a c program and here is the structure I am using 

struct EngineParts{

    int serial_number;
    unsigned int year_of_manufacture;
    unsigned int quantity;
    char *material;

}*Eparts;

And I am getting the following error

`Automobile.c:79:5: error: invalid type argument of unary ‘*’ (have ‘unsigned int’)` 

`Automobile.c:80:5: error: invalid type argument of unary ‘*’ (have ‘int’)` 

`Automobile.c:81:5: error: invalid type argument of unary ‘*’ (have ‘unsigned int’)`

in these three lines

 *new->quantity = quantity;
 *new->serial_number = serial_number;
 *new->year_of_manufacture = year_of_manufacture;

Here is the complete implementation

void automobile_add_part(const int serial_number,
        const unsigned int year_of_manufacture,
        const unsigned int quantity , 
        const char *material){
    /*
     * Store the address to the latest part
     */
   struct EngineParts *new ;
   new = (Eparts+available_number_of_parts);

    // Copying a String is a little bit complicated
    // First memory is allocated for the string 
    *new->material = (char *)calloc(strlen(material),sizeof(char));
    //Then the string is copied
    strcpy((char *)*new->material,material);    

    *new->quantity = quantity;
    *new->serial_number = serial_number;
    *new->year_of_manufacture = year_of_manufacture;

    available_number_of_parts++;
}

PS : I have checked out the following questions ,

error: invalid type argument of ‘unary *’ (have ‘int’)

Invalid type argument of -> C structs

but they don't seem to help me.

Any suggestions on how to solve the problem ?

Upvotes: 2

Views: 8855

Answers (4)

lostyzd
lostyzd

Reputation: 4523

no need * for new->quantity

the -> is shortcut for (*new).quantity

Upvotes: 1

Griwes
Griwes

Reputation: 9029

The -> operator dereferences the pointer, so use of additional * is not required. And results in error.

Upvotes: 1

millimoose
millimoose

Reputation: 39950

The -> operator already dereferences the pointer for you.

new->serial_number is equivalent to (*new).serial_number, both of which seem like what you want.

Upvotes: 6

Jon
Jon

Reputation: 437376

Do it this way:

new->quantity = quantity;

The extra pointer dereference (*new->quantity) is an error: new->quantity is an int, not any kind of pointer so the compiler complains.

Dereferencing the new pointer (is it even legal to have a variable named such?) is already done through operator->.

Upvotes: 4

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