为什么只有第一行打印在csv文件中？

Question

Using the code below the output gets printed like this:

1     20
3     21
4     45
5     55 

which is correct, but, while printing it in a csv file it gets printed like this(below) even though codes for printing and writing in csv file are inside the same brackets(same place),

1     20

which means only the first line is printed. Why is it not printing the remaining other lines in the csv file ? Is there any difference between printing the output and writing it in a csv file in c++ ?

This is the block of code :

ofstream outfile;
double average = (((double) total) / num);
cout << lFraction << " , " << arraySize << " " << average << endl;
outfile.open("results1.csv");
outfile << arraySize << " , " << average << endl ;
outfile.close();

Answer 1

Every time you open the file that deletes the existing contents of the file.

You have two options:

• Open the file once, write all the results, and then close it.
• Use the app end flag so that the file contents aren't deleted and new data is written at the end: outfile.open("results1.csv", ios::app);

The first option is recommended because constantly opening and closing the same file wastes time.