c语言问题 输入一个非字母运行结果会多出一个非字母字符

Question

输入一个非字母运行结果会多出一个非字母字符
#include<stdio.h>
int main()
{
char ch;
printf("Enter a character:"); scanf("%c",&ch);
if(ch>='A'&&ch<='Z'){
ch=ch+32;
}
else if(ch>='a'&&ch<='z')
ch=ch-32;
else
printf("%c is not a letter",ch);
printf("%c",ch);
return 0;

Answer 1

#include<stdio.h>
int main()
{
char ch;
printf("Enter a character:"); scanf("%c",&ch);
if(ch>='A'&&ch<='Z'){
ch=ch+32;
printf("%c",ch);
}
else if(ch>='a'&&ch<='z')
{ch=ch-32;
printf("%c",ch);
}
else
printf("%c is not a letter",ch);

return 0;