pointer.cpp

// hello.cpp by Bill Weinman <http://bw.org/>
#include <cstdio> // or use <iostream>
#include <iostream>
using namespace std;

void iterateThroughArray(int *array, int size){
    cout<< "use function" << endl;
    for(int i = 0; i<size; i++){
        cout<< *array << " ";
        array++;
    }
}


void iterateThroughMatrix(int matrix[][4], int height, int width){
    cout << "use the function" << endl;
    cout << matrix << endl;
    for(int i= 0 ; i < height; i++){
        for( int j=0; j < width; j++){
            cout << matrix[i][j] << " ";
        }
        cout << endl;
    }
}

int main()
{
    cout << "-------------------------------------------------------------" << endl;
    cout << "Pointer iteration on array" << endl;
    cout << "-------------------------------------------------------------" << endl;
    cout << "" << endl;

    int a[6] = {0,1,2,3,4,5};

    int *ptr = &a[0];

    while(*ptr != 5){
        ptr++;
        std::cout << "value: " << *ptr << std::endl;
        std::cout << "Address: " << &ptr << std::endl;
        std::cout << "Pointer: " << ptr << std::endl;
    }

    //Use a function
    iterateThroughArray(a,6);


    cout << "" << endl;
    cout << "-------------------------------------------------------------" << endl;
    cout << "Pointer iteration on 2D matrix" << endl;
    cout << "-------------------------------------------------------------" << endl;
    cout << "" << endl;


    int matrix[3][4] = {
            {1,2,3,4},
            {5,6,7,8},
            {9,10,11,12}
    };

    int *matrixPtr = &matrix[0][0];

    cout << "Matrix [0] " << matrix[0] << endl;
    cout << "MatrixPtr: " << matrixPtr << endl;// same as matrix[0]
    cout << "Matrix [0][0] " << matrix[0][0] << endl;

    int matrixHeight = sizeof(matrix) / sizeof(matrix[0]);
    int matrixWidth = sizeof(matrix[0]) / sizeof(matrix[0][0]);

    cout << "Matrix Height: " << matrixHeight << endl;// same as matrix[0]
    cout << "Matrix Width: " << matrixWidth << endl;

    //normal iteration
    cout << ""<< endl;
    cout << "Normal array Iteration" << endl;

    for(int i= 0 ; i < matrixHeight; i++){
        for( int j=0; j < matrixWidth; j++){
            cout << matrix[i][j] << " ";
        }
        cout << endl;
    }

    //pass to a function

    iterateThroughMatrix(matrix,3,4);

    //Playing with pointer
    cout << "" << endl;
    cout << "Playing with pointer" << endl;

    cout << "" << endl;
    cout << "Using matrix index pointer" << endl;

    for(int i = 0; i < matrixHeight; i++){
        for(int j = 0; j < matrixWidth; j++){
            cout << *matrix[i] << " "; //Printing first element of each row
        }
        cout<<endl;
    }

    cout << "" << endl;
    cout << "Using pointer on first element" << endl;


    for(int i = 0; i < matrixHeight; i++){
        for(int j = 0; j < matrixWidth; j++){
            cout << *matrixPtr << " ";
            matrixPtr++;
        }
        cout<<endl;
    }

    cout << "" << endl;
    cout << "-------------------------------------------------------------" << endl;
    cout << "Pointer iteration on 3D matrix" << endl;
    cout << "-------------------------------------------------------------" << endl;
    cout << "" << endl;

    int matrix3D[3][3][4] = {
            {
                    {1,2,3,4},
                    {5,6,7,8},
                    {9,10,11,12}
            },
            {
                    {13,14,15,16},
                    {17,18,19,20},
                    {21,22,23,24}
            },
            {
                    {25,26,27,28},
                    {29,30,31,32},
                    {33,34,35,36}
            }
    };

    int *matrixPtr3D = &matrix3D[0][0][0];

    cout << "Matrix [0] " << matrix3D[0] << endl;
    cout << "Matrix [0][0] " << matrix3D[0][0] << endl;
    cout << "MatrixPtr: " << matrixPtr3D << endl;// same as matrix[0]
    cout << "Matrix [0][0][0] " << matrix3D[0][0][0] << endl;
    //Pointer values
    cout << "*Matrix [0] " << *matrix3D[0] << endl; //point to pointer matrix3D[0][0]
    cout << "**Matrix [0] " << **matrix3D[0] << endl; //point to pointer matrix3D[0][0]
    cout << "*Matrix [0][0] " << *matrix3D[0][0] << endl;
    cout << "*MatrixPtr: " << *matrixPtr3D << endl;// same as matrix[0]


    int matrix3dDepth = sizeof(matrix3D) / sizeof(matrix3D[0]);
    int matrix3dHeight = sizeof(matrix3D[0]) / sizeof(matrix3D[0][0]);
    int matrix3dWidth = sizeof(matrix3D[0][0]) / sizeof(matrix3D[0][0][0]);

    cout << "Matrix Depth: " << matrix3dDepth << endl;// same as matrix[0]
    cout << "Matrix Height: " << matrix3dHeight << endl;// same as matrix[0]
    cout << "Matrix Width: " << matrix3dWidth << endl;

    //normal iteration
    cout << ""<< endl;
    cout << "Normal array Iteration" << endl;
    for(int k = 0; k< matrix3dDepth; k++){
        for(int i= 0 ; i < matrix3dHeight; i++){
            for( int j=0; j < matrix3dWidth; j++){
                cout << matrix3D[k][i][j] << " ";
            }
            cout << endl;
        }
        cout<<""<<endl;

    }

    //Playing with pointer
    cout << "" << endl;
    cout << "Playing with pointer" << endl;

    cout << "" << endl;
    cout << "Using matrix index pointer" << endl;

    for(int k = 0; k< matrix3dDepth; k++){
        for(int i = 0; i < matrixHeight; i++){
            for(int j = 0; j < matrixWidth; j++){
                cout << **matrix3D[i] << " "; //Printing first element of each row
            }
            cout<<endl;
        }
    }


    cout << "" << endl;
    cout << "Using pointer on first element" << endl;

    for(int k = 0; k< matrix3dDepth; k++){
        for(int i = 0; i < matrix3dHeight; i++){
            for(int j = 0; j < matrix3dWidth; j++){
                cout << *matrixPtr3D << " ";
                matrixPtr3D++;
            }
            cout<<endl;
        }
        cout<<""<<endl;
    }


    return 0;
}