title: Getting errors: "error: conflicting types for ‘call_celsius’ " and "note: previous implicit declaration of ‘call_celsius’ was here"
body: <p>i cannot get this code to compile in gcc. ive tried changing the call_celsius to calculate as well as changing it from uppercase to lowercase. im not sure if its because i didnt declare a variable which i dont think is the case, or if i did the call function wrong.</p>
  
  <pre><code>/* Homework 1 Question 2 */
  
  /* Purpose: Takes a depth (in kilometers) inside the earth */
  /* as input data; Computes and displays the temperature at */
  /* depth in degrees Celsius and degrees Fahrenheit.        */
  
  #include &lt;stdio.h&gt;
  
  int main(void)
  {
  
  /* Declare Variables */
  
  double depth;
  double Celsius;
  double Fahrenheit;
  
  /* Obtain Data */
  
  printf("Please enter depth(in kilometers) inside the Earth:  ");
  scanf("%lf",&amp;depth);
  
  /* Calculate */
  
  Celsius = call_celsius(depth);
  Fahrenheit = call_fahrenheit(Fahrenheit);
  
  /* Output */
  
  printf("The temperature at %lf kilometers is %lf degrees Celsius and %lf degrees       Fahrenheit",depth, Celsius, Fahrenheit);
  
  return 0;
  }
  
  double call_celsius(double depth)
  {
  return((10 * depth) + 20);
  }
  
  double call_fahrenheit(double Celsius)
  
  {
  return((1.8 * Celsius) + 32);
  }
  </code></pre>
  
  <p>these are the errors i receive </p>
  
  <pre><code>homework1question2.c:35:8: error: conflicting types for ‘call_celsius’
  double call_celsius(double depth)
      ^
  homework1question2.c:25:11: note: previous implicit declaration of ‘call_celsius’ was here
  Celsius = call_celsius(depth);
         ^
  homework1question2.c:40:8: error: conflicting types for ‘call_fahrenheit’
  double call_fahrenheit(double Celsius)
      ^
  homework1question2.c:26:14: note: previous implicit declaration of ‘call_fahrenheit’ was    here
  Fahrenheit = call_fahrenheit(Fahrenheit);
  </code></pre>