为何在很多次编程时，总出现[Error] ld returned 1 exit status？这个是由于那些错误造成的啊

#include <stdio.h>
#define N 30        /*宏常量：以最大范围定义，便于数据改动及避免数据出界*/
void Readscore(long ID[],int score[],int n);         /*Readscore()函数原型*/
void SortID(long ID[],int score[],int n);
int Finddate(long ID[],long x,int n);
int main()
{
    int score[N],n,mid;
    long ID[N],x;                    /*以长整型接收学号数据*/
    printf("Input n:\n");
    scanf("%d",&n);
    Readscore(ID,score,n);         /*数组名作为函数实参调用函数 Readscore() */
    SortID(ID,score,n);
    printf("Input your aim ID:\n");
    scanf("%ld",&x);
    mid=Finddata(ID,x,n);
    if(mid==-1)
    {
        printf("No student %ld",x);
    }
    else
        printf("Ranking is:%d Score is:%d",mid,score[mid]);
    return 0;
}
void Readscore(long ID[],int score[],int n)      /*函数功能：读入学生成绩数据和学号*/
{
    printf("Please pay attention to your date:score>0 and ID should be different\n"); /*提示用户输入合法数据*/
    int i;
    for(i=0;i<n;i++)
    {
        scanf("%ld %d",&ID[i],&score[i]);   
    }
}
void SortID(long ID[],int score[],int n)   /*函数功能：排序成绩*/
{
    int i,j,k,agent;
    long sagent;
    for(i=0;i<n-1;i++)
    {
        for(j=i+1;j<n;j++)
        {
            if(ID[j]<ID[i])             /*按学号的升序排序*/
            {
                agent=score[j];
                score[j]=score[i];
                score[i]=agent;
                sagent=ID[j];
                ID[j]=ID[i];
                ID[i]=sagent;
            }
        }            
    }
}
int Finddate(long ID[],long x,int n)
{
    int low=0,high=n-1,mid;
    while(low<=high)
    {
        mid=(high+low)/2;
        if(x>ID[mid])
        low=mid+1;
        else if (x<ID[mid])
            high=mid-1;
        else
        return mid;        
    }
    return -1;
}
源代码是这个，求大佬帮看啊实在找不到

低级错误。。谢谢~~

是的呀，已经解决啦，是因为函数名的错误