曾经遇到的报错或警告

array type has incomplete element type

代码：

#define MaxSize 50                                                                                                   │2
//定义学生的结构类型                                                                                                 │请输入圆柱体的底圆半径和高：10 8
struct stduent{                                                                                                      │该圆柱体的体积为：2512.00
    int num;                                                                                                         │1-计算圆球的体积2-计算圆柱体的体积3-计算圆椎体的体积其他-退出程序运行
    char name[10];                                                                                                   │3
    int computer, english, math;//这种定义形式                                                                       │请输入圆锥体的底圆半径和高：10 8
    double average;                                                                                                  │该圆锥体的体积为：837.33
};                                                                                                                   │1-计算圆球的体积2-计算圆柱体的体积3-计算圆椎体的体积其他-退出程序运行
int count = 0;                                                                                                       │^C
//新增学生                                                                                                           │[root@localhost example]# 
void add_student(struct student students[]);                                                                         │
//查询学生信息，根据学生编号                                                                                         │
void search_student(struct student students[], int num);                                                             │
//输出全部学生的信息                                                                                                 │
void output_student(struct student students[]);

报错信息：

9-1.c:17:33: error: array type has incomplete element type
 void add_student(struct student students[]);
                                 ^
9-1.c:17:25: warning: ‘struct student’ declared inside parameter list [enabled by default]
 void add_student(struct student students[]);
                         ^
9-1.c:17:25: warning: its scope is only this definition or declaration, which is probably not what you want [enabled by default]
9-1.c:19:36: error: array type has incomplete element type
 void search_student(struct student students[], int num);
                                    ^
9-1.c:19:28: warning: ‘struct student’ declared inside parameter list [enabled by default]
 void search_student(struct student students[], int num);
                            ^
9-1.c:21:36: error: array type has incomplete element type
 void output_student(struct student students[]);
                                    ^
9-1.c:21:28: warning: ‘struct student’ declared inside parameter list [enabled by default]
 void output_student(struct student students[]);

原因：
定义结构时，名称写错了！！！ student写成了stduent，编译报错，提示的我一愣愣的

warning: data definition has no type or storage class [enabled by default]

翻译
警告：数据定义没有类型或存储类[默认启用]
可能的原因
函数外，写赋值表达式