############### TABLICA WSKAŹNIKÓW #########################
#include <stdio.h>
#include <stdlib.h>
int sum(int a, int b){
return a + b;}

int substract(int a, int b){
return a - b;}

int multi (int a, int b){
return a * b;}

int (*p[3])(int a, int b);

int main()
{
    int result;
    p[0] = sum;
    p[1] = substract;
    p[2] = multi;

    result = (*p[2])(4,2);
    printf("%d", result);
    return 0;
}


############### TABLICE DWUWYMIAROWE #########################
#include <stdio.h>
#include <stdlib.h>


int jedynki(int liczba){
    int count = 0;
    while (liczba){
        liczba &= liczba - 1;
        count++;
    }
    return count;
}


int main()
{
    int wiersze;
    int kolumny;
    unsigned int currentMax = 0;
    int row;
    printf("Podjac liczbê wierszy:\n");
    scanf("%d", &wiersze);
    printf("Podaj liczbê kolumn:\n");
    scanf("%d", &kolumny);

    int** xy;
    xy = (int**)malloc(wiersze*sizeof(unsigned int));
    for (int i = 0; i < wiersze; i++){
        xy[i] = (int*)malloc(2 * sizeof(unsigned int));

    }
    for (int i = 0; i < wiersze; i++){
            printf("Uzupe³nij wiersz");
        for (int j = 0; j < kolumny; j++){
            scanf("%d", &(xy[i][j]));
        }
    }


    printf("Tablica zostanie wydrukowana");
    for (int i = 0; i < wiersze; i++){
        for (int j = 0; j < kolumny; j++){
            printf("%d", xy[i][j]);
        }
        printf("\n");
    }

    for (int i = 0; i<wiersze; i++){
        unsigned int jedyneczki = 0;
        for (int j = 0; j<kolumny; j++){
            jedyneczki += jedynki(xy[i][j]);
        }
        if (jedyneczki > currentMax){
            currentMax = jedyneczki;
            row = i;
        }
    }
    printf("%d", currentMax);
    for (int j = 0; j<kolumny; j++){
        printf("%d", xy[row][j]);
    }

    free(xy);
    return 0;
}

################ DYNAMICZNE TABLICE JEDNOWYMIAROWE #####################

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int N;
    printf("Podaj wielkoϾ tablicy");
    scanf("%d", &N);

    int *x = (int*)malloc(N*sizeof(int));

    for (int i = 0; i < N; i++){
        scanf("%d", &(x[i]));
    }

    printf("drukowanie tablicy");
    for (int i = 0; i<N; i++){
        printf("%d\n", x[i]);
    }
}

############## CZYTANIE WORD BY WORD ###################
#include <stdio.h>
#include <stdlib.h>



int main()
{
    char costam[30];
    FILE *fpointer = fopen("tekst.txt", "ra");
    while (!feof(fpointer)){
        fscanf(fpointer, "%s", costam);
        printf("Next word is: %s\n", costam);
    }
    return 0;
}

############# CZYTANIE CHAR BY CHAR ###################
#include <stdio.h>
#include <stdlib.h>



int main()
{
    char ch;
    FILE *fpointer = fopen("tekst.txt", "ra");
    while (!feof(fpointer)){
        ch = fgetc(fpointer);
        printf("Next sign is: \"%c\"\n", ch);
    }
    return 0;
}


############## CZYTANIE LINE BY LINE ##################
#include <stdio.h>
#include <stdlib.h>



int main()
{
    char line[255];
    FILE *fpointer = fopen("tekst.txt", "ra");
    while (!feof(fpointer)){
        fgets(line, 255, fpointer);
        printf("Next line is: %s\n", line);
    }
    fclose(fpointer);
    return 0;
}


############## APPENDING AND READING ####################
#include <stdio.h>
#include <stdlib.h>



int main()
{
    char line[255];
    FILE *fpointer = fopen("tekst.txt", "a+");
    fprintf(fpointer, "\nuwaga dodaje linie");
    fseek(fpointer, 0, 0);
    while (!feof(fpointer)){

        fgets(line, 255, fpointer);
        printf("Next line is: %s\n", line);
    }
    fclose(fpointer);
    return 0;
}

############ SZESNASTKOWY ##############

#include <stdio.h>
#include <stdlib.h>


void heksa(int liczba, char* heksadecymalna){
    char szesnastkowa[20];
    char tablica[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
    int reszta;
    int index = 0;
    while(liczba != 0){
        reszta = liczba % 16;
        liczba = liczba / 16;
        szesnastkowa[index] = tablica[reszta];
        index++;
    }
    int heksaindex = 0;
    int nowy_index = index - 1;
    for (nowy_index; nowy_index >= 0; nowy_index--){
        heksadecymalna[heksaindex] = szesnastkowa[nowy_index];
        heksaindex++;
    }
}

int main()
{
    char arr[15];
    heksa(375098, arr);
    printf("Konwersja: %s\n", arr);
    return 0;
}
############ TABLICA STRUKTUR ############
#include <stdio.h>
#include <stdlib.h>

int main()
{
    FILE *fpointer = fopen("tekst.txt", "r");

    struct Student{
        int age;
    };

    struct Student s[5];
    int counter = 0;
    int age1;
    while (!feof(fpointer)){
           fscanf(fpointer, "%d\n", &age1);
           s[counter].age = age1;
           counter++;

    };

    printf("%d", s[3].age);
    return 0;
}
########### NOTATKI ##################
- przekazywanie stringu do struktury
    ctrcpy(student1.name, "Jim");

- uzyskiwanie adresu
    printf("%p", &age);

- storing pointer variable
    int *pAge = &age;

- dereferencing pointer
    printf("%d", *pAge);

- wprowadzanie stałej
    const int NUM = 5;

-getting double
    scanf("%lf", &gpa);

- getting string
    scanf("%s", name);

- getting line of text
    scanf(name, 20, stdin);