将参数从传递给qsort（）函数<stdlib.h>

Question

This is the data type that I declared:

struct Element{
    char name[21], symbol[4];
    double atomicMass;
    int valence;
};
typedef struct Element myElements;
myElements data[20];

If I just want to pass the name members of

data[20] 

to qsort(), how to do that?

Not sure if this would be the correct way to pass to the function:

qsort(data->name, 20, sizeof(myElements), compare);

Answer 1

You don't pass just member. Right way is to write a helper compare function which compares 2 elements by their name and use it.

static int
cmpElement(const void *p1, const void *p2)
{
    return strcmp(((const Element *) p1)->name, ((const Element *) p2)->name);
}

qsort(data, 20, sizeof data[0], cmpElement);