输入一串字母 将里面的元音输出希望各位大佬能给指导

#include <stdio.h>
#define SIZE 100
int main() 
{
    
	void fun(char a[], char b[]);
		char a[SIZE];
	char b[SIZE];
	scanf_s("%s", a,SIZE);
	fun(a,b);
	return 0;

		

}
void fun( char a[], char b[])
{
    
	int number = 0;
	for (int i = 0; i < SIZE; i++)
		if (a[i] == 'a' || a[i] == 'e' || a[i] == 'i' || a[i] == 'o' || a[i] == 'u')
			b[number++] = a[i];
	for (int i = 0; i < number; i++)
		printf("%c", b[i]);
}