错误：在不是结构或联合的东西中请求成员“长度”

Question

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

 struct a{
    int length;
};

static int a2(int a[]){

 int y = 0;
 int x = 0;
 for (int i=0; i<a.length; i++)
    {
        if (a[i]%2 == 0)
        y += a[i];
 else
    x += a[i];
 }
 return x - y;
}

int main()
{
    int a[] = {1};
    printf("%d\n", a2(a));
    return 0;
}

when I run this code I receive the following error "error: request for member 'length' in something, not a structure or union" can anyone help me to understand the error and how to rectify the code? Thanks

Answer 1

The name of structure and the name of variables are not related.

The argument a is a pointer ( int a[] in function arguments has the same meaning as int* a ) and it doesn't have members.

You have to pass the length of array to pass to functions aside from (the pointer to the first element of) the array.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static int a2(int a[], int a_length){

    int y = 0;
    int x = 0;
    for (int i=0; i<a_length; i++)
    {
        if (a[i]%2 == 0)
           y += a[i];
        else
           x += a[i];
    }
    return x - y;
}

int main()
{
    int a[] = {1};
    printf("%d\n", a2(a, sizeof(a) / sizeof(*a)));
    return 0;
}