title: I was running a a program and came by this error. what does it mean?
body: <pre><code>#if __APPLE_CC__
  #include &lt;GLUT/glut.h&gt;
  #else
  #include &lt;windows.h&gt;
  #include &lt;gl\gl.h&gt;
  #include &lt;gl\glu.h&gt;
  #include &quot;glut.h&quot;
  #endif
  
  
  
  #include &lt;math.h&gt;
  #include &lt;stdio.h&gt;
  #include &quot;scene.h&quot;
  #include &lt;string.h&gt;
  
  
  
  
  extern float g_t;
  
  
  
  
  //function prototypes for the local functions
  void drawCone(float x, float y, float z, float radius, float height, int nSides, float startColor[3], float endColor[3]);
  
  void drawBox(float left, float bottom, float front,
      float length, float height, float depth);
  
  /*
     this function is called whenever OpenGL needs to redraw
     the screen
     
  */
  void drawScene(void)
  {
    float startColor[3] = { 0.5, 0.0, 0.0}, endColor[3] = {1.0, 1.0, 0.0};
  //    drawCone(0,-1,0, 0.5, 1.0, 20, startColor, endColor);
   //   drawCone(0,1,0, 0.5, -1.0, 20, startColor, endColor);
  
  //    glEnable(GL_CULL_FACE);
  //    glCullFace(GL_BACK);
      
      
      //tabletop
      drawBox(-1, 1, 0.5, 2.0, 0.1, 1);
      
      //left, front leg
      drawBox(-1, 0, 0.5, .1, 1, .1);
      
      glColor3f(0,0,0);
      glutWireTorus(0.1, .25, 12, 16);
      
      glTranslatef(0.0, 1.25, 0.0);
      glutWireTeapot(0.2);
      glTranslatef(0.0, -1.25, 0.0);
  
  
  }//drawScene
  
  void drawCone(float x, float y, float z, float radius, float height, int nSides, float startColor[3], float endColor[3])
  {
      int i, j, next;
      float angle;
      
      float circlePoints[100][3];
      float colors[100][3];
      
      //first calculate the points on a circle and the color for each point
      
      for(i = 0; i &lt; nSides; ++i)
      {
         angle = 2* M_PI/nSides * i;
         circlePoints[i][0] = radius * sin(angle) + x;
         circlePoints[i][1] = y;
         circlePoints[i][2] = radius * cos(angle) + z;
         
         colors[i][0] = (endColor[0]- startColor[0])/ nSides * i + startColor[0];
         colors[i][1] = (endColor[1]- startColor[1])/ nSides * i + startColor[1];
         colors[i][2] = (endColor[2]- startColor[2])/ nSides * i + startColor[2];
      }
       //draw the cone
      glBegin(GL_TRIANGLES);
      for(i = 0; i &lt; nSides; ++i)
      {
          next = (i + 1) % nSides;
          glColor3f(colors[i][0], colors[i][1], colors[i][2]);
          glVertex3f(circlePoints[next][0], circlePoints[next][1], circlePoints[next][2]);
          glVertex3f(x, y + height, z);
          
          glVertex3f(circlePoints[i][0], circlePoints[i][1], circlePoints[i][2]);
         // glVertex3f(x, y + height, z);
      }
      glEnd();
      
      //draw the circle
      glBegin(GL_POLYGON);
      for(i = 0; i &lt; nSides; ++i)
      {
          glColor3f(startColor[0], startColor[1], startColor[2]);
          glVertex3f(circlePoints[i][0], circlePoints[i][1], circlePoints[i][2]);
      }
       glVertex3f(circlePoints[0][0], circlePoints[0][1], circlePoints[0][2]);
      glEnd();
  }
  
  /*
              x,X left
              y,Y bottom
              z Z front
              l L length
              h H height
              d D depth
  */
                 
  void handleKey(char key)
  {
      printf(&quot;key = %c\n&quot;, key);
  
  }
  
  void drawBox(float left, float bottom, float front,
      float length, float height, float depth)
      {
      float right = left + length;
      float top = bottom + height;
      float back = front - depth;
      //draw the front
      glBegin(GL_QUADS);
      
      //front
      glColor3f(1.0, 0.0, 0.0);
      glVertex3f(left, bottom, front);
      glVertex3f(right, bottom, front);
      glVertex3f(right, top, front);
      glVertex3f(left, top, front);
      
      //left
      glColor3f(0.0, 1.0, 0.0);
      glVertex3f(left, bottom, front);
      glVertex3f(left, top, front);
      glVertex3f(left, top, back);
      glVertex3f(left, bottom, back);
      
      //back
      glColor3f(0.0, 0.0, 1.0);
      glVertex3f(left, bottom, back);
      glVertex3f(left, top, back);
      glVertex3f(right, top, back);
      glVertex3f(right, bottom, back);
      
      //top
      glColor3f(0.0, 1.0, 1.0);
      glVertex3f(left, top, front);
      glVertex3f(right, top, front);
      glVertex3f(right, top, back);
      glVertex3f(left, top, back);
  
      //bottom
      glColor3f(1.0, 0.0, 1.0);
      glVertex3f(left, bottom, front);
      glVertex3f(right, bottom, front);
      glVertex3f(right, bottom, back);
      glVertex3f(left, bottom, back);
      
      glEnd();
  }
  
  
  
  
  
  
  
  
  
  
   
  
  
  </code></pre>
  <p>Undefined symbols for architecture x86_64:
  &quot;_main&quot;, referenced from:
  implicit entry/start for main executable
  ld: symbol(s) not found for architecture x86_64
  clang: error: linker command failed with exit code 1 (use -v to see invocation)</p>
  <h2>This the error i got but i couldn't figure it out</h2>
  <p>i copy pasted this because i needed more words in body</p>
  <p>Ld /Users/dahirali/Library/Developer/Xcode/DerivedData/scene-ccsieluddlpredauupsijrhisooo/Build/Products/Debug/scene normal (in target 'scene' from project 'scene')
  cd /Users/dahirali/Desktop/1101/scene
  /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -target x86_64-apple-macos10.15 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk -L/Users/dahirali/Library/Developer/Xcode/DerivedData/scene-ccsieluddlpredauupsijrhisooo/Build/Products/Debug -F/Users/dahirali/Library/Developer/Xcode/DerivedData/scene-ccsieluddlpredauupsijrhisooo/Build/Products/Debug -filelist /Users/dahirali/Library/Developer/Xcode/DerivedData/scene-ccsieluddlpredauupsijrhisooo/Build/Intermediates.noindex/scene.build/Debug/scene.build/Objects-normal/x86_64/scene.LinkFileList -Xlinker -object_path_lto -Xlinker /Users/dahirali/Library/Developer/Xcode/DerivedData/scene-ccsieluddlpredauupsijrhisooo/Build/Intermediates.noindex/scene.build/Debug/scene.build/Objects-normal/x86_64/scene_lto.o -Xlinker -export_dynamic -Xlinker -no_deduplicate -Xlinker -dependency_info -Xlinker /Users/dahirali/Library/Developer/Xcode/DerivedData/scene-ccsieluddlpredauupsijrhisooo/Build/Intermediates.noindex/scene.build/Debug/scene.build/Objects-normal/x86_64/scene_dependency_info.dat -o /Users/dahirali/Library/Developer/Xcode/DerivedData/scene-ccsieluddlpredauupsijrhisooo/Build/Products/Debug/scene</p>