What does this line mean? Her purpose?

Question

C++ / C#

The only thing I understand is that the search_for array is equal to the number of characters entered -1 (let's say "green" i.e. 7 - 1 = 6 [due to the fact that the array indexing starts from 0, not 1]). And we add '\0' to the value of the last index .
Why bring it in?
His role?

Answer 1

The search_for array first reads the user-entered string ending in "Enter" (0x10), then this character Enter is replaced by 0x00, which in C is a sign of the end of the line.
That is, after fgets in the array, we have the entered string, line feed, \0.
After the specified string, the entered string remains in the array, \0, \0 (the second "zero" no longer carries a load).

Answer 2

You can find a full explanation of the meaning of "null-terminated string" here Null-terminated string , but in short, in C-like languages, this is a terminating string.

Answer 3

The operation with the assignment of 0 in this form is completely superfluous here, because fgets in the previous step already wrote 0 at the end of the line. Without this, strlen would not be able to calculate the correct length of the string.
I would also understand something like this: search_for[79]=0; - insurance against buffer overflows, although this is redundant if you rely on the correct operation of fgets. But we probably won't be checking every implementation of fgets, so this statement seems more logical than the one in the example.