Same old identifier not found error in C++

Hello I've been trying to resolve the issue that I've been having with the code I am working on at the moment. I have looked at other posts but couldn't find anything relevant. Basically, i have added all the necessary files: header and source files but still getting errors. One of many is "'setValue': identifier not found". For some reason, it doesn't recognize any of the functions from my header file. Anyways, here is the portion of the code that pertains to the error. I can't show all the code as its huge:

Header DoubleVector.h:

 #pragma once
    #pragma warning(disable : 4251)

    #ifndef DOUBLEVECTOR_H_
    #define DOUBLEVECTOR_H_

    #define _USE_MATH_DEFINES   // need to use M_PI
    #include <math.h>
    #include "PMath.h"

// whole bunch of constructors and functions declarations, which I won't show

// this is one of the functions that's causing trouble
    void    SetValue(long index,double val);

Source DoubleVector.cxx:

void CDoubleVector::SetValue(long index,double val)
{
    if(index < 0 || index >= m_nSize)
    {
        //string message("Index out of range of vector.");
        //throw PMathError(message);
        throw PMathError("Error: index(%d) out of range. <- void SetValue(long index, double val) in DoubleVector.cxx",index); // tested
    }

    m_pData[index] = val;
}

File where I am calling my functions variogram.cc:

#include "variogram.h"
#include "DoubleVector.h"


    void Variogram::estimate() {

        base_multimin_function_fdf fdf;

        fdf.n = _spatialCorrFunc.param.size(); 

        fdf.f = &minimizationf;
        fdf.df = &minimizationfd;
        fdf.fdf = &minimizationfdf;
        fdf.params = this;
        long iter = 0;
        int status;
        //gsl_vector *x = gsl_vector_alloc(fdf.n); 

        for (int i = 0; i < fdf.n; ++i) {
            if(i < 3)


     //gsl_vector_set(x, i, sqrt(_spatialCorrFunc.param[i]));
         //Greg: void SetValue(long index, double val) as an alternative //to 开发者_运维问答gsl_vector_set(...)
            SetValue(i,sqrt(_spatialCorrFunc.param[i]));
            else//kappa
             SetValue(i, _spatialCorrFunc.param[i]);
        }

This thing is driving me crazy but I am sure it's something stupid that I'm not seeing. Thanks in advance.

void    SetValue(long index,double val); // Notice that beginning `S` is uppercase.

setValue => S should be upper case at the beginning in the methods call.

You're using a member function without having an instance. You need to create an object and then call it on that object:

CDoubleVector dv;
...
dv.SetValue(i, sqrt(_spatialCorrFunc.param[i])); // etc

You can only use the plain SetValue(something) when you're inside a member function in the class that has the member SetValue, in which case it's shorthand for this->SetValue(something). That way the compiler knows what object you're talking about.

Not to mention your capitalisation is was wrong.