谁能看一下为什么sleep（）的那个代码无法运行

Question

#include<stdlib.h>
#include<stdio.h>
int main()
{
    char arr1[] = "happy everyday!";
    char arr2[] = "###############";
    int l = 0;
    int sz = sizeof(arr1) / sizeof(arr1[0]);
    int r = sz - 2;
    while (l <=r)
    {
        printf("%s\n", arr2);
        arr2[l] = arr1[l];
        arr2[r] = arr1[r];
        sleep(1000);
        system("cls");
        l++;
        r--;
    }
    return 0;

}

Answer 1

1
#include <windows.h>
2
Sleep的s大写