指针不匹配，指针冲突

在写结构体的时候，我发现了这样的一个现象

#include<stdio.h>

int prt(struct student *stu);

struct student
{
    char *name;
    float score[3];
};



int main()
{

    struct student stu;
    stu.name = "cxk";
    stu.score[0] = 98.5;
    stu.score[1] = 97.5;
    stu.score[2] = 99.5;
    prt( &stu );
}

int prt(struct student *stu)
{
    printf("name : %s\n",stu -> name);
    printf("socre[0] : %f\n",stu -> score[0]);
    printf("socre[1] : %f\n",stu -> score[1]);
    printf("socre[2] : %f\n",stu -> score[2]);
}

这样写会有报错
指针不兼容，冲突。
我在网上搜了半天没搞懂这是为什么
但如果将函数声明放在main函数中

#include<stdio.h>


struct student
{
    char *name;
    float score[3];
};



int main()
{
    int prt(struct student *stu);
    struct student stu;
    stu.name = "cxk";
    stu.score[0] = 98.5;
    stu.score[1] = 97.5;
    stu.score[2] = 99.5;
    prt( &stu );
}

int prt(struct student *stu)
{
    printf("name : %s\n",stu -> name);
    printf("socre[0] : %f\n",stu -> score[0]);
    printf("socre[1] : %f\n",stu -> score[1]);
    printf("socre[2] : %f\n",stu -> score[2]);
}

就没有错误，希望有大神可以指点一下

C语言要求先定义后使用
int prt(struct student *stu);
要放在
struct student
定义后面。

以下2个写法都可以

#include<stdio.h>
struct student
{
    char *name;
    float score[3];
};

int prt(struct student *stu);

int main()
{

    struct student stu;
    stu.name = "cxk";
    stu.score[0] = 98.5;
    stu.score[1] = 97.5;
    stu.score[2] = 99.5;
    prt( &stu );
}

int prt(struct student *stu)
{
    printf("name : %s\n",stu -> name);
    printf("socre[0] : %f\n",stu -> score[0]);
    printf("socre[1] : %f\n",stu -> score[1]);
    printf("socre[2] : %f\n",stu -> score[2]);
    return 0;
}

#include<stdio.h>

struct student;
int prt(struct student *stu);

struct student
{
    char *name;
    float score[3];
};

int main()
{

    struct student stu;
    stu.name = "cxk";
    stu.score[0] = 98.5;
    stu.score[1] = 97.5;
    stu.score[2] = 99.5;
    prt( &stu );
}

int prt(struct student *stu)
{
    printf("name : %s\n",stu -> name);
    printf("socre[0] : %f\n",stu -> score[0]);
    printf("socre[1] : %f\n",stu -> score[1]);
    printf("socre[2] : %f\n",stu -> score[2]);
    return 0;
}