title: call to undefined function in function main()
body: <p>whenever i use a function which is called in main function, it gives this error: Call to undefined function in function main()
  i am using turbo c++ compiler version 4.5 and windows vista ultimate service pack 2
  Can you tell which header file or something else is to be used. I am beginner in  C language.</p>
  
  <p>An example which produces this error:</p>
  
  <pre><code>#include&lt;stdio.h&gt; 
  
  main( ) 
  { 
    int i ; 
    int marks[ ] = { 1, 2, 3, 4, 5, 6, 7 } ; 
  
    for ( i = 0 ; i &lt;= 6 ; i++ ) display ( marks[i] ) ; 
  } 
  
  display ( int m ) 
  { 
    printf ( "%d ", m ) ; 
  }
  </code></pre>