error: taking address of temporary [-fpermissive]

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I have this code which I can compile successfully in MS VS 2010, but with eclipse CDT & MinGW (gcc 4.72) I have three errors:

..\find_classes.h:90:17: error: taking address of temporary [-fpermissive]
..\find_classes.h:94:51: error: invalid initialization of non-const reference of type ‘cv::Mat&’ from an rvalue of type ‘cv::Mat’
..\find_classes.h:82:8: error: in passing argument 2 of ‘double get_distance(cv::Mat&, cv::Mat&)’

Anyone willing me to explain what is actual problem and how to fix this?

Code is here:

#ifndef _FIND_CLASSES_H_
#define _FIND_CLASSES_H_
#include "asmlibrary.h"
#include <string>
#include <fstream>

using namespace std;

const int N_FEATURES = 7;
int N_EXPRESSIONS;
int N_SAMPLES;
int N_POINTS;
char** EXP_NAMES;
int *classLabelArray;
double *classPointArray;
cv::Mat classLabels;
cv::Mat classPoints;
//cv::Mat classDistances;
cv::Mat diff;


void read_config_from_file(string filename){
    // ifstream file(filename, ios::in); // NMB
    ifstream file(filename.c_str(), ios::in);
    if(!file.is_open()){
        cout << "error opening file: " << filename << endl;
        exit(1);
    }

    file >> N_EXPRESSIONS >> N_SAMPLES;
    N_POINTS = N_EXPRESSIONS * N_SAMPLES;

    EXP_NAMES = new char*[N_EXPRESSIONS];   //read expression names from file
    for(int i=0 ; i<N_EXPRESSIONS ; i++){
        EXP_NAMES[i] = new char[11];
        file >> EXP_NAMES[i];
    }

    classLabelArray = new int[N_POINTS];    //create classLabelArray (independent from file)
    for(int i=0 ; i<N_POINTS ; i++){
        classLabelArray[i] = i/N_SAMPLES;
    }

    classPointArray = new double[N_POINTS*N_FEATURES];  //read feature values for each class from file
    for(int i=0 ; i<N_POINTS*N_FEATURES ; i++){
        file >> classPointArray[i];
    }

    file.close();

    classLabels = cv::Mat(1, N_POINTS, CV_32SC1, classLabelArray);
    classPoints = cv::Mat(N_POINTS, N_FEATURES, CV_64FC1, classPointArray);
    //classDistances = cv::Mat(N_POINTS, 1, CV_64FC1);
    diff = cv::Mat(1, N_FEATURES, CV_64FC1);
}

void config(string filename, int n_expressions, int n_samples, string *exp_names){
    // ofstream file(filename, ios::out);
    ofstream file(filename.c_str(), ios::in);
    if(!file.is_open()){
        cout << "error opening file: " << filename << endl;
        exit(1);
    }

    N_EXPRESSIONS = n_expressions;
    N_SAMPLES = n_samples;
    file << N_EXPRESSIONS << endl << N_SAMPLES << endl;
    cout << N_EXPRESSIONS << endl << N_SAMPLES << endl;
    N_POINTS = N_EXPRESSIONS * N_SAMPLES;

    EXP_NAMES = new char*[N_EXPRESSIONS];
    for(int i=0 ; i<N_EXPRESSIONS ; i++){
        cout<< exp_names[i] << endl;

        EXP_NAMES[i] = strdup(exp_names[i].c_str());
        file << EXP_NAMES[i] << endl;
    }

    file.close();
}

double get_distance(cv::Mat& p32, cv::Mat& p64) { // error: in passing argument 2 of ‘double get_distance(cv::Mat&, cv::Mat&)’
    for(int i=0; i<N_FEATURES; i++)
        diff.at<double>(0,i) = p32.at<float>(0,i) - p64.at<double>(0,i);
    return cv::norm(diff);
}

cv::Mat get_class_weights(cv::Mat instance) {
    cv::Mat weights = cv::Mat(1,N_EXPRESSIONS, CV_64FC1);
    cvZero(&(CvMat)weights); // <-- error: taking address of temporary [-fpermissive]
    double dist;

    for(int i = 0; i<N_POINTS; i++) {
        dist = get_distance(instance, classPoints.row(i)); // error: invalid initialization of non-const reference of type ‘cv::Mat&’ from an rvalue of type ‘cv::Mat’
        // classDistances.at<double>(i,0) = dist;
        // printf("%d ", classLabels.at<int>(0,i));
        weights.at<double>(0, classLabels.at<int>(0,i)) += dist;
        //printf("%.2f ",dist);
    }
    //cout <<endl;
    // printf("%lf %lf\n", weights.at<double>(0,0), weights.at<double>(0,1));

    for(int i = 0; i < N_EXPRESSIONS; i++)
        weights.at<double>(0,i) = exp(-weights.at<double>(0,i));

    double sum = cv ...