把一个字母'a'输入一个int型变量导致的错误

题目：编写一个程序，将用户输入的十进制短整型正数n转换成二进制数。如果用户输入负数或者读入错误，则要求用户重新输入。
输入提示信息："n="
**输入格式："%hd"  /* short 类型 */
输出信息："the binary number is "
**输出格式要求："%d" 
程序运行示例如下：
n=37
the binary number is 0000000000100101

 1 #include <stdio.h>
 2 #include <math.h>
 3 #include <ctype.h>
 4 int main(){
 5     short n;
 6     int cnt = 0;
 7     printf("n=");
 8     scanf("%hd", &n);
 9     while(n <= 0){
10         printf("n=");
11         scanf("%hd", &n);
12     }
13     int v[17];
14     long long binary = 0;
15     do{
16         v[cnt + 1] = n % 2;
17         n /= 2;
18         cnt++;
19     }while(n);
20     for (int i = 0; i < cnt; i++){
21         binary += v[i + 1] * pow(10, i);
22     }
23     printf("the binary number is %016lld", binary);
24     return 0;
25 }

 1 #include <stdio.h>
 2 #include <math.h>
 3 void trans(short n, short b[]);
 4 int main()
 5 {                            
 6     short b[16], n, i, read_in = 0;
 7     for (i = 0; i <= 15; i++)
 8     {                            
 9         b[i] = 0;
10     }
11     do
12     {                            
13         printf("n=");
14         read_in = scanf("%hd", &n);
15         while(getchar()!=‘\n‘);   //1
16     }while( n<0||read_in <1 );   //1
17     trans(n, b);
18     printf("the binary number is ");
19     for (i = 15; i >= 0; i--)
20     {                            
21         printf("%d", b[i]);   //1
22     }
23     printf("\n");
24     return 0;
25 }                            
26 void trans(short n, short b[])  //2
27 {                            
28     int i = 0;
29     while (n != 0)
30     {                            
31         b[i] = n % 2;  //1
32         i++; 
33         n /= 2;    //1
34     }
35     
36 }                            

1 do
2 {                            
3     printf("n=");
4     read_in = scanf("%hd", &n);
5     while(getchar()!=‘\n‘);   //1
6 }while( n<0||read_in <1 );   //1

while(getchar()!=‘\n‘);