title: fflush(stdin) ANSI C
body: <p>I am a beginner in ANSI C, and I have a question, it may be silly question and I am sorry for it.</p>
  
  <pre><code>#include&lt;stdio.h&gt;
      main()
      {
            int age;
            printf("Hello World!\n");
            printf("Please enter your age: ");
            scanf("%d", &amp;age);
            printf("You entered %d\n", age);
            fflush(stdin);
            getchar();
      }
  </code></pre>
  
  <p>It is my second program to learn scanf function.
  My question is :
    I know that <strong>printf</strong>, <strong>scanf</strong>, <strong>fflush</strong>, <strong>stdin</strong>, and <strong>getchar</strong> are defined in <strong>stdio.h</strong> but only when I use <strong>fflush(stdin)</strong> I must put <strong>#include&lt;<em>stdio.h</em>></strong>, but when use any other method I can remove that line #include.</p>