指针练习班级成绩

1.求第一门课程的平均分
2.找出有两门以上不及格的学生
3.找出平均分在90分以上或全部课程在85分以上的学生

#include<stdio.h>
#include<math.h>
#include<string.h>
#define M 4
#define N 5
void Average(int *arr,int n);
void TwoFail(int *arr);
void OutputFail(int (*p)[N],int i);
void GoodStudents(int *arr);

int main(void){
    int arr[M][N]={{34,56,88,99,89},{27,88,99,67,78},{99,90,87,86,89},{78,89,99,56,77}};
    Average(arr,0);
    TwoFail(arr);
    GoodStudents(arr);
}

void Average(int *arr,int n){
    int (*p)[N]=arr;
    float average=0;
    for(int i=0;i<M;i++){
        average+=*(*(p+i)+n);
    }

    printf("the %d class average is %f:",n,average/M);

}

void TwoFail(int *arr){
    int (*p)[N]=arr;int flag=0;
    for(int i=0;i<M;i++){
            flag=0;
        for(int j=0;j<N;j++){
            if(*(*(p+i)+j)<60)
                flag++;
        }

        if(flag==2){
           OutputFail(p+i,i);
           continue;
        }

    }
}

void OutputFail(int (*p)[N],int i){
    printf("NO.%d student's fail.\n",i);
    float average=0;
    printf("scores are:");
    for(int j=0;j<N;j++){
        printf("%d ",*(*p+j));
        average+=*(*p+j);
    }

    printf("\nAverage is %f\n",average/N);
}

void GoodStudents(int *arr){
    int ave90=1,ab85=1;
    float average;
    int (*p)[N]=arr;
    int Good[M];//save good student flag.
    for(int i=0;i<M;i++){
        Good[i]=0;
    }
    for(int i=0;i<M;i++){
        average=0;ave90=1;ab85=1;
        for(int j=0;j<N;j++){
                average+=*(*(p+i)+j);
            if(*((*p+i)+j)<85){
                ab85=0;
            }
        }

        average/=N;
        if(average<90)ave90=0;

        if(ave90||ab85)Good[i]=1;

    }

    for(int i=0;i<M;i++)
    if(Good[i])
        printf("%d is a good student.\n",i);


}