Question

when I use c++ to process a file ,I found there is always a blank line in the end of file .Someone says that vim will append an ‘\n’ in the end of file,but when I use gedit,it also has the same question.Can anyone tell me the reason?

1 #include<iostream> 
2 #include<fstream> 
3  
4 using namespace std; 
5 const int K = 10; 
6 int main(){ 
7         string arr[K];
8         ifstream infile("test1");
9         int L = 0;
10         while(!infile.eof()){
11             getline(infile, arr[(L++)%K]);
12         }
13         //line
14         int start,count;
15         if (L < K){
16             start = 0;
17             count = L;
18         }
19         else{
20             start = L % K;
21             count = K;
22         }
23         cout << count << endl; 
24         for (int i = 0; i < count; ++i)
25             cout << arr[(start + i) % K] << endl;
26         infile.close();
27         return 1;
28 }

while test1 file just:
abcd
but the program out is :
2
abcd

(upside is a blank line)

Answer 1

while(!infile.eof())

infile.eof() only is true after you tried to read beyond the end of the file. So the loop tries to read one more line than there is and gets an empty line on that attempt.