Question

What is the difference between read() and readline() in C#?

Maybe we don’t use it but in my academy the only difference is that one has “line” and the other don’t have…
In c++, there is “cin” and it has “endl” to add line.
Can somebody tell me the difference?

Answer 1

Do you mean TextReader.Read and TextReader.ReadLine?

One overload of TextReader.Read reads characters into a buffer (a char[]), and you can specify how many characters you want it to read (as a maximum). Another reads a single character, returning an int which will be -1 if you’ve reached the end of the reader.

TextReader.ReadLine reads a whole line as a string, which doesn’t include the line terminator.

As far as I’m aware, endl is more commonly used in conjunction with cout in C++:

cout << "Here's a line" << endl;

In .NET you’d use

writer.WriteLine("Here's a line")

to accomplish the same thing (for an appropriate TextWriter; alternatively use Console.WriteLine for the console).

EDIT: Console.ReadLine reads a line of text, whereas Console.Read reads a single character (it’s like the parameterless overload of TextWriter.Read).

Console.ReadLine() is basically the same as Console.In.ReadLine() and Console.Read() is basically the same as Console.In.Read().

EDIT: In answer to your comment to the other answer, you can’t do:

int x = Console.ReadLine();

because the return type of Console.ReadLine() is a string, and there’s no conversion from string to int. You can do

int x = Console.Read();

because Console.Read() returns an int. (Again, it’s the Unicode code point or -1 for “end of data”.)

EDIT: If you want to read an integer from the keyboard, i.e. the user types in “15” and you want to retrieve that as an integer, you should use something like:

string line = Console.ReadLine();
int value;
if (int.TryParse(line, out value))
{
    Console.WriteLine("Successfully parsed value: {0}", value);
}
else
{
    Console.WriteLine("Invalid number - try again!");
}