What is the logic behind while loop behavior in this case?

Kal Kal

My code simply Creates a refrence variable of StreamReader object that reads a TextFile, After that using a while loop to retrive data from the TextFile.

StreamReader sr = new StreamReader("File.txt");
string line = "";
while (line != null)
{
line = sr.ReadLine();
Console.WriteLine(line);
}

So, forgive my innocent question : The condition in the While loop is TRUE, so why it doesn't return an infinite loop ? instead it retrives the data from "File.txt" then it breaks the loop?

All what I know as a newbie programmer is that if the condition of the loop is TRUE keep it going until it turns to FALSE then the loop will break; itself.

Could somebody explain the logic behind this scenario please!

2 Replies

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Ramesh Palanivel8y ago
Accepted answer
Hi kal kal,

The below Line performing as increment section.

Like

int i=0;
while(i<=10)
{
//statement body
++i;//Increment section
}
StreamReader sr = new StreamReader("File.txt");

string line = "";

while (line != null)
{
line = sr.ReadLine(); //This is the increment section reading the line from text file until the line is empty or null

Console.WriteLine(line);

}
Kal Kal8y ago
Thanks, Ramesh

Your answer opened a next door for me.

I have tried this logic on another simple code to approve it my self.
So, I come with this...
string[] names = new string[] { "aaa", "bbb" , "ccc" , "ddd", null };

string line = "";
int i = 0;
while (line != null)
{

    line = names[i];

    Console.WriteLine(line);

    i++;
}
Considering that retriving the indexed elements from an array has the same process of what sr.ReadLine() method does except that incrementing it via i++ has been done implicitly on the original code.
Thank you again for your cooporation.