共十个学生，每名学生五门课程，这个小程序是用来输出每名学生的平均成绩、每门课程的平均成绩、获取最高分数的人和该科以及学生的平均分方差。
代码如下：
#include<stdio.h>
#include<math.h>
void test1(double students[10][5],double average_stu[10]);
void test2(double students[10][5],double average_sub[5]);
void test3(double students[10][5]);
void test4(double average_stu[10]);
int main()
{
    int i,j;
    char x;
    double students[10][5];
    double average_stu[10];
    double average_sub[5];
    ABC:
    printf("would you want to test ?(y/Y or n/N):");
    scanf("%c",&x);
    if(x=='n'||x=='N') return 0;
    printf("please input the students' score:\n");
    for(i=0;i<=9;i++)
    {
        for(j=0;j<=4;j++) scanf("%lf",&students[i][j]);
    }
    test1(students,average_stu);
    test2(students,average_sub);
    test3(students);
    test4(average_stu);
    printf("the END\n");
    goto ABC;
    return 0;
}

void test1(double students[10][5],double average_stu[10])
{
    printf("the average score of the students\n");
    int i,j;
    double sum=0;
    for(i=0;i<=9;i++)
    {
        sum=0;
        for(j=0;j<=4;j++)
        {
            sum=sum+students[i][j];
        }
        average_stu[i]=sum/5;
    }
    for(i=0;i<=9;i++) printf("the student%d\t%lf\n",i+1,average_stu[i]);
    printf("--------------------------------------------------------------------\n");
}

void test2(double students[10][5],double average_sub[5])
{
    printf("the average score of subject\n");
    int i,j;
    double sum=0;
    for(j=0;j<=4;j++)
    {
        sum=0;
        for(i=0;i<=9;i++) sum=sum+students[i][j];
        average_sub[j]=sum/10;
    }
    for(i=0;i<=4;i++) printf("the subject%d\t%lf\n",i+1,average_sub[i]);
    printf("--------------------------------------------------------------------\n");
}

void test3(double students[10][5])
{
    printf("the high subject and student\n");
    double max;
    int i,j,m,n;
    max=students[0][0];
    for(i=0;i<=9;i++)
    {
        for(j=0;j<=4;j++)
        {
            if(max<students[i][j])
            {
                max=students[i][j];
                m=i;
                n=j;
            }
        }
    }
    printf("the NO1 is student%d's subject%d\t%lf\n",m+1,j+1,max);
    printf("--------------------------------------------------------------------\n");
}

void test4(double average_stu[10])
{
    printf("the var score of this class\n");
    double sum=0,var,sum1=0;
    int i;
    for(i=0;i<=9;i++)
    {
        sum=sum+pow(average_stu[i],2);
        sum1=sum1+average_stu[i];
    }
    sum1=pow(sum1/10,2);
    var=sum/10-sum1;
    printf("the var of the students' score is %lf\n",var);
    printf("--------------------------------------------------------------------\n");
}
现在问题是：我已经在函数体中声明了这些变量(上面我描红的地方)，但编译时判定为未声明
而后我将这些变量全部声明为全局变量，这样编译才通过，这是什么原因呢？
ps:我在以c++格式编译时能够通过(因为我的编译器默认是首先以.cpp文件编译的，后来我将其保存为.c文件才发现问题)

好像c99中说这种是可以的吧

我的编译器对c99支持貌似不是很好诶  有点老了 还是mingw2.95的