title: Is there any function to get an unlimited input string from standard input
body: <p>The condition is:</p>
  
  <p><strong>I want to input a line from standard input, and I don't know the size of it, maybe very long.</strong></p>
  
  <p>method like <code>scanf</code>, <code>gets</code>need to know the max length you may input, so that your input size is less than your buffer size. </p>
  
  <p>So Is there any good ways to handle it?</p>
  
  <p>Answer must be only in C, <strong>not C++</strong>, so c++ string is not what I want. I want is C standard string, something like <code>char*</code> and end with <code>'\0'</code>.</p>