如何在数组的末尾添加一个定义长度为C的字符?

I have a C assignment where we use an array with a length of 10 to store chars into. The professor made a point where we can't use null to specify the end of the array. The array is to hold a name and we read from stdin. When the name is bigger than 10 characters, we print out it's too long. Here is my code so far and it doesn't work because when I press enter to submit the name, it uses that as a character and I have to get to 10 before anything happens, which results in it saying it's too long of a name, which isn't the desired result.I have a C assignment where we use an array wit