expected primary expression

This is a discussion on expected primary expression within the C Programming forums, part of the General Programming Boards category; Hi, I'm having a problem with this code. Basically, I get an error at line 63 expected primary-expression before "double" ...

  1. #1
    Registered User
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    Mar 2007
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    8

    expected primary expression

    Hi, I'm having a problem with this code.
    Basically, I get an error at line 63 expected primary-expression before "double" and also at line 63 expected `;' before "double"

    The original problem computes the angle gamma, but I need to make the gamma computation into a function and then call that function to calculate it. Any info would be much appreciated!
    Code:
    /*------------------------------------------------------------*/
    /*  Program chapter4_3                                        */
    /*                                                            */
    /*  This program determines the distance between two points   */
    /*  that are specified with latitude and longitude values     */
    /*  that are in the Northern Hemisphere.                      */
     
    #include <stdio.h>
    #include <math.h>
    #define PI 3.141593
     
    int main(void)
    {
       /*  Declare variables and function prototype.  */
       double lat1, long1, lat2, long2;
       double gc_distance(double lat1, double long1, 
                          double lat2, double long2);
       double angle(double x1, double y1, double z1,
                    double x2, double y2, double z2);
    
       setbuf( stdout, 0); /* make stdout unbuffered */
    
       /*  Get locations of two points.  */
       printf("Enter latitude north and longitude west ");
       printf("for location 1: \n");
       scanf("%lf %lf",&lat1,&long1);
       printf("Enter latitude north and longitude west ");
       printf("for location 2: \n");
       scanf("%lf %lf",&lat2,&long2);
     
       /*  Print great circle distance.  */
       printf("Great Circle Distance: %.0f miles \n",
               gc_distance(lat1,long1,lat2,long2));
                 
       /*  Exit program.  */
       return 0;
    }
    /*------------------------------------------------------------*/
    /*  This function computes the distance between two           */     
    /*  points using great circle distances.                      */                          
     
    double gc_distance(double lat1, double long1, 
                       double lat2, double long2)
    { 
    
       /*  Declare variables.  */
       double rho, phi, theta, gamma, dot, dist1, dist2,
              x1, y1, z1, x2, y2, z2;
              
       /*  Convert latitude,longitude to rectangular coordinates.  */
       rho = 3960;
       phi = (90 - lat1)*(PI/180.0);
       theta = (360 - long1)*(PI/180.0);
       x1 = rho*sin(phi)*cos(theta);
       y1 = rho*sin(phi)*sin(theta);
       z1 = rho*cos(phi);
       phi = (90 - lat2)*(PI/180.0);
       theta = (360 - long2)*(PI/180.0);
       x2 = rho*sin(phi)*cos(theta);
       y2 = rho*sin(phi)*sin(theta);
       z2 = rho*cos(phi);
     
    gamma = double angle(double x1, double y1, double z1,
                    double x2, double y2, double z2);
       /*  Compute angle between vectors.  
       dot = x1*x2 + y1*y2 + z1*z2;
       dist1 = sqrt(x1*x1 + y1*y1 + z1*z1);
       dist2 = sqrt(x2*x2 + y2*y2 + z2*z2);
       gamma = acos(dot/(dist1*dist2)); */
     
       /*  Compute and return great circle distance.  */
       return gamma*rho;
    }
    /*------------------------------------------------------------*/
       double angle(double x1, double y1, double z1,
                    double x2, double y2, double z2)
    {
           double dot, dist1, dist2, gamma1;         
       dot = x1*x2 + y1*y2 + z1*z2;
       dist1 = sqrt(x1*x1 + y1*y1 + z1*z1);
       dist2 = sqrt(x2*x2 + y2*y2 + z2*z2);
       gamma1 = acos(dot/(dist1*dist2));
       
       return gamma1;
    }

  2. #2
    Just Lurking Dave_Sinkula's Avatar
    Join Date
    Oct 2002
    Posts
    5,006
    Move the prototypes above main, and then call the function like this:
    Code:
       gamma = angle(x1, y1, z1, x2, y2, z2);
    Not like this:
    Code:
    gamma = double angle(double x1, double y1, double z1,
                    double x2, double y2, double z2);
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

  3. #3
    Registered User
    Join Date
    Mar 2007
    Posts
    8
    Thank you for the quick reply!

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