Linear Interpolation C code for X and Y axis - compile errors

[controlsguy]

When trying to compile, I am receiving errors which I am assuming are pretty generic and common:

lin_interp.c:21: error: expected '=', ',', ';', 'asm' or '__attribute__' before '{' token
lin_interp.c:100: error: expected '{' at end of input

I am not very familiar with C code, so any help would be greatly appreciated. I am just trying to get the code to work for now. I have created a program similar to this which worked in C++, but the code isn't jiving in C.

// Lin_Interp.c : Defines the entry point for the console application.
//
#include "PACRXPlc.h"  /* Include file applicable for all targets */
#include "ctkInitCBlock.h"
#include "string.h"
#include "math.h"
#include "stdlib.h"
#include <time.h>
#include <ctype.h>
#include <stdio.h>
/* Constants / #defines  */
// Print-Out on console "XY LIMIT ARRAY"  XYlim    
int GefMain  (T_WORD *Y0,       /* Input Param 1  */
             T_WORD  *Y1,      /* Input Param 2  */
             T_WORD  *Y2,      /* Input Param 3  */
             T_WORD  *X0,      /* Input Param 4  */
             T_WORD  *X1,      /* Input Param 5  */
             T_WORD  *X2,      /* Input Param 6  */
             T_WORD  *Z1)      /* Output Param 7 */

int main (){ 
   label1:
    int i=0,j=0,X0=0,Y0=0,X1=0,Y1=0;
      double X,Y,Fxy=0,Fxy0=0,FxyOld=0,Fxy1=0;
// "Y Axis LIMIT FUNCTION - CORRECCTED Y ARRAY"  TY
      double TY[11]={0,10,20,30,40,50,60,70,80,90,100};
// "X Axis LIMIT FUNCTION - CORRECTED X ARRAY"  TX
      double TX[11]={0,10,20,30,40,50,60,70,80,90,100};
      // "Lin Interp OP LIMIT FUNCTION - Lin Interp LIMIT ARRAY"  XYlim
    double XYlim[11][11]={0.0,10.0,20.0,30.0,40.0,50.0,60.0,70.0,80.0,90.0,100.0,
			  0.0,10.0,20.0,30.0,40.0,50.0,60.0,70.0,80.0,90.0,100.0,
			  0.0,10.0,20.0,30.0,40.0,50.0,60.0,70.0,80.0,90.0,100.0,
			  0.0,10.0,20.0,30.0,40.0,50.0,60.0,70.0,80.0,90.0,100.0,
			  0.0,10.0,20.0,30.0,40.0,50.0,60.0,70.0,80.0,90.0,100.0,
			  0.0,10.0,20.0,30.0,40.0,50.0,60.0,70.0,80.0,90.0,100.0,
			  0.0,10.0,20.0,30.0,40.0,50.0,60.0,70.0,80.0,90.0,100.0,
			  0.0,10.0,20.0,30.0,40.0,50.0,60.0,70.0,80.0,90.0,100.0,
			  0.0,10.0,20.0,30.0,40.0,50.0,60.0,70.0,80.0,90.0,100.0,
			  0.0,10.0,20.0,30.0,40.0,50.0,60.0,70.0,80.0,90.0,100.0,
			  0.0,10.0,20.0,30.0,40.0,50.0,60.0,70.0,80.0,90.0,100.0};
      cout<< "    X0="<<X0<< ".    X1="<<X1<<"   i="<<i<<endl;
     cout<< "    Y0="<<Y0<< ".    Y1="<<Y1<<"   j="<<j<<endl<<endl;

      cout<< "    KGV_X0["<<X0<<"]="<<TX[X0]<< "    KGV_X1["<<X1<<"]="<<TX[X1]<<endl;   
      cout<< "    SPD_Y0["<<Y0<<"]="<<TY[Y0]<<"    SPD_Y1["<<Y1<<"]="<<TY[Y1]<<endl<<endl;

      cout<< "    XYlim["<<X0<<"]["<<Y0<<"]="<<XYlim[X0][Y0]<<endl;
      cout<< "    XYlim["<<X1<<"]["<<Y0<<"]="<<XYlim[X1][Y0]<<endl;
      cout<< "    XYlim["<<X0<<"]["<<Y1<<"]="<<XYlim[X0][Y1]<<endl;
      cout<< "    XYlim["<<X1<<"]["<<Y1<<"]="<<XYlim[X1][Y1]<<endl<<endl;
      //calculate F(X,Y), and print-out on console.
    //Using one equation to calculate F(X,Y).  The problem with this one equation method is if X0 = X1, then most of the equation's products go to zero.
      //To see this problem, enter an known X value like 48.  Then enter a Y value that is not known or on the curve.  Example would be X=48 and Y=92.5
      //The 3-equation result will be the correct value of 9.1815, the single equation result will be the result of X=48 and Y=90 or 8.672
    FxyOld=XYlim[X0][Y0]+((X-TX[X0])/(TX[X1]-TX[X0])*(XYlim[X1][Y0]-XYlim[X0][Y0]))+
            ((Y-TY[Y0])/(TY[Y1]-TY[Y0])*(X-TX[X0])/(TX[X1]-TX[X0])*(XYlim[X1][Y1]-XYlim[X0][Y1]-XYlim[X1][Y0]+XYlim[X0][Y0]));
   //Using 3 equations to calculate F(X,Y).  Using this method prevents the problem that occurs when X0 = X1 and Y0 does not equal Y1.
   Fxy0=XYlim[X0][Y0]+((X-TX[X0])/(TX[X1]-TX[X0])*(XYlim[X1][Y0]-XYlim[X0][Y0]));
   Fxy1=XYlim[X0][Y1]+((X-TX[X0])/(TX[X1]-TX[X0])*(XYlim[X1][Y1]-XYlim[X0][Y1]));
   Fxy=Fxy0+((Y-TY[Y0])/(TY[Y1]-TY[Y0])*(Fxy1-Fxy0));

   cout<< "    Fxy["<<X<<"]["<<Y<<"]= "<<Fxy<<"   (3-equation result)"<<endl<<endl;//Three equation result to screen
   cout<< "    FxyOld["<<X<<"]["<<Y<<"]= "<<FxyOld<<"   (1-equation result)"<<endl<<endl;    //Single equation result to screen
   goto label1;  //Start program over
	for (j=0;j<11;j++){             
        for (i=0;i<11;i++){
         cout<< XYlim[i][j] << " "; //Display the curve
            }
      cout << endl;
      }
      // Input X, ensure it is in the range.
      cout<<endl<< "Please enter X value:";
      cin>>X;     
      while (X >100.0 || X<0.0){
                  cout<<endl<< "Your X value is either greater than 100.0 or smaller than 0.0, Please re-enter again:";
            cin>>X;
            }
      // Input Y, ensure it is in the range.
    cout<<endl<< "Please enter Y value:";
      cin>>Y;
      while (Y >100.0 || Y<0.0){
                  cout<<endl<< "Your Y value is either greater than 100 or smaller than 0, Please re-enter again:";
            cin>>Y;
            }     
      cout<<endl<< "    X="<<X<< ".    Y="<<Y<<endl<<endl;

      //Select the correct X0&Y0, X1&Y1
          for (i=0;i<10;i++){ 
            if (X >= TX[i]) X0=i;
            else break;
      }
      X1=X0+1;

    for (j=0;j<12;j++){ 
            if (Y >= SPD[j]) Y0=j;
            else break;
      }

      return 0;
}

[S_M_A]

int GefMain  (T_WORD *Y0,       /* Input Param 1  */
             T_WORD  *Y1,      /* Input Param 2  */
             T_WORD  *Y2,      /* Input Param 3  */
             T_WORD  *X0,      /* Input Param 4  */
             T_WORD  *X1,      /* Input Param 5  */
             T_WORD  *X2,      /* Input Param 6  */
             T_WORD  *Z1);      /* Output Param 7 */

You also have to implement it if you intend to use it (otherwise just remove it)

Pay some attention to how you format the code, spaces and aligned {} improve the readability a lot.

Goto isn't exactly the first thing you should think on using but anyway here are some more compilation issues:

- The label has to be set after the variables.
- Neither cin/cout nor << exists in plain C.
- SPD isn't declared
- Neither X or Y are initialized before being used

[Paul McKenzie]

I am not very familiar with C code, so any help would be greatly appreciated. I am just trying to get the code to work for now. I have created a program similar to this which worked in C++, but the code isn't jiving in C.

Please note that C and C++ are two different languages with differing rules as to what is valid and what isn't valid. Trying to go back and forth between the two languages, especially when you don't have the experience of both, will just confuse you.

So which language are you really trying to learn and use, C or C++?

Regards,

Paul McKenzie

[controlsguy]

Please note that C and C++ are two different languages with differing rules as to what is valid and what isn't valid. Trying to go back and forth between the two languages, especially when you don't have the experience of both, will just confuse you.

So which language are you really trying to learn and use, C or C++?

Regards,

Paul McKenzie

Paul, sorry for the confusion - The code needs to be in "C". Thank you for your help.

[Paul McKenzie]

Paul, sorry for the confusion - The code needs to be in "C". Thank you for your help.

If that's the case, then you can't use C++. Your attempt is making my point concerning confusion between the two languages.

Why are you using cout and cin, which are C++ concepts? You should be using printf() and scanf(), respectively. If you need to write this in 'C', then get 'C' books and tutorials, not C++ tutorials/books. You should forget that C++ even exists.

Regards,

Paul McKenzie

[controlsguy]

If that's the case, then you can't use C++. Your attempt is making my point concerning confusion between the two languages.

Why are you using cout and cin, which are C++ concepts? You should be using printf() and scanf(), respectively. If you need to write this in 'C', then get 'C' books and tutorials, not C++ tutorials/books. You should forget that C++ even exists.

Regards,

Paul McKenzie

Thanks Paul. Will do.

I can't find any topics on the "<<" I am using. How do these normally work?

[Paul McKenzie]

Thanks Paul. Will do.

I can't find any topics on the "<<" I am using. How do these normally work?

Well, here may be more confusion between C and C++.

In C++, there is a concept called operator overloading. This means that you can take an operator, for example, the "+", "-", "<<", etc, and define different meanings for them, depending on the type of arguments that are used with the operators. If the "<<" is not overloaded, it is the "shift-left n bits" operator. However for streams, whenever a "<<" is used "<<" takes on a different meaning, which is "stream the data to x".

In 'C', there is no such thing as operator overloading. Therefore the << has one and only one meaning -- shift left n bits.

So if you mean "<<" with respect to C++ streams, then there is plenty of topics on this, since streams are a core topic in C++.

Regards,

Paul McKenzie

[controlsguy]

Well, here may be more confusion between C and C++.

In C++, there is a concept called operator overloading. This means that you can take an operator, for example, the "+", "-", "<<", etc, and define different meanings for them, depending on the type of arguments that are used with the operators. If the "<<" is not overloaded, it is the "shift-left n bits" operator. However for streams, whenever a "<<" is used "<<" takes on a different meaning, which is "stream the data to x".

In 'C', there is no such thing as operator overloading. Therefore the << has one and only one meaning -- shift left n bits.

So if you mean "<<" with respect to C++ streams, then there is plenty of topics on this, since streams are a core topic in C++.

Regards,

Paul McKenzie

Thanks for your feedback, Paul.

If this is the case, how can I replace these operators in my code with the equivalent in C?

[S_M_A]

See http://msdn.microsoft.com/en-us/library/wc7014hz.aspx and http://msdn.microsoft.com/en-us/library/9y6s16x1.aspx