为什么全局函数调用结构体变量参数时报出这三个错误

first

Compiling source file(s)...
Sizeof.cpp
Sizeof.cpp:19: error: expected unqualified-id before "return"
Sizeof.cpp:19: error: expected `,' or `;' before "return"
Sizeof.cpp:19: error: expected declaration before '}' token
Sizeof.exe - 3 error(s), 0 warning(s)


源代码如下：（cpp文件独立运行，无头文件）
#include <iostream>
using namespace std;

struct A{
    int  i;
};
void func1(A *a,int j);
void func2(A *a);

int main(){
    A *a ;
    int j = 5;
    func1(a,j);
    func2(a);
   
return 0;
}

return 0;}


void func1(A *a,int j){
    a->i = j;
    cout<<"A->i ="<<a->i<<endl;
}
   
void func2(A *a){
    cout<<"A->i ="<<a->i<<endl;
}