3. cviko ZPrPr2

//1.priklad
#include <stdio.h>

void nacitaj(double *a, double *b);
double obsah(double a, double b);
double obvod(double a, double b);

int main(){
    double a, b, (*p_fn)();
    char c;
    nacitaj(&a, &b);
    while (getchar() != '\n');
    if ((c = getchar()) == 's')
        p_fn = obsah;
    else if (c == 'o')
        p_fn = obvod;
    else{
        printf("Neplatna volba\n");
        return 1;
    }
    printf("%g\n", (*p_fn)(a, b));
    return 0;
}

void nacitaj(double *a, double *b){
    scanf("%lf %lf", a, b);
}

double obsah(double a, double b){
    return (a*b);
}

double obvod(double a, double b){
    return (2 * a + 2 * b);
}

//2.priklad
#include <stdio.h>
#define NULL 0

int cislica(char c);
int male_pismeno(char c);
int biely(char c);
int velke_pismeno(char c);
int zisti(FILE *fr, int(*p_fn)());
void otvor(void **p_fr);

int main(){
    int n, i, (*p_fn)();
    char volba;
    FILE *fr=NULL;
    otvor(&fr);
    if (fr == NULL)
        return 1;
    scanf("%d", &n);
    for (i = 0; i < n; i++){
        scanf("\n%c", &volba);
        switch (volba){
            case 'b': p_fn = biely; break;
            case 'v': p_fn = velke_pismeno; break;
            case 'm': p_fn = male_pismeno; break;
            case 'c': p_fn = cislica; break;
            default:
                printf("Neznama volba\n");
                continue;
        }
        printf("%d\n", zisti(fr, (*p_fn)));
    }
    if (fclose(fr) == EOF){
        printf("Subor sa nepodarilo zatvorit\n");
        return 1;
    }
    return 0;
}

void otvor(void **p_fr){
    *p_fr = fopen("ZNAKY.TXT", "r");
}

int zisti(FILE *fr, int(*p_fn)()){
    int pocitadlo = 0;
    char c;
    while ((c = getc(fr)) != EOF){
        pocitadlo += (*p_fn)(c);
    }
    rewind(fr);
    return pocitadlo;
}

int cislica(char c){
    if (c >= '0' && c <= '9')
        return 1;
    return 0;
}

int male_pismeno(char c){
    if (c >= 'a' && c <= 'z')
        return 1;
    return 0;
}

int biely(char c){
    if (c == '\n' || c == '\t' || c == ' ')
        return 1;
    return 0;
}

int velke_pismeno(char c){
    if (c >= 'A' && c <= 'Z')
        return 1;
    return 0;
}

//3.priklad
#include <stdio.h>

int main(){
    char *p_str;
    int i, n;
    scanf("%d\n", &n);
    p_str = (char*)malloc(n*sizeof(char));
    for (i = 0; i < n; i++)
        *(p_str + i) = getchar();
    for (--n; n >= 0; n--)
        putchar(*(p_str + n));
    putchar('\n');
    return 0;
}

//4.priklad
#include <stdio.h>

int scitaj();
int odcitaj();
int nasob();
int del();

int main(){
    int(*p_fn)();
    char volba;
    while ((volba = getchar()) != 'e'){
        while (getchar() != '\n');
        switch (volba){
        case 's': p_fn = scitaj; break;
        case 'o': p_fn = odcitaj; break;
        case 'n': p_fn = nasob; break;
        case 'd': p_fn = del; break;
        default:
            printf("Operacia nie je podporovana\n");
            continue;
        }
        printf("%d\n", (*p_fn)());
        while (getchar() != '\n');
    }
    return 0;
}

int scitaj(){
    int a, b;
    scanf("%d %d", &a, &b);
    return a + b;
}

int odcitaj(){
    int a, b;
    scanf("%d %d", &a, &b);
    return a - b;
}

int nasob(){
    int a, b;
    scanf("%d %d", &a, &b);
    return a * b;
}

int del(){
    int a, b;
    scanf("%d %d", &a, &b);
    return a / b;
}

//5.priklad
#include <stdio.h>

int main(){
    int *a, *b, c;
    a = (int*)malloc(sizeof(int));
    b = (int*)malloc(sizeof(int));
    scanf("%d %d %d", a, b, &c);
    printf("%d + %d + %d = %d\n", *a, *b, c, (*a) + (*b) + c);
    return 0;
}

//6.priklad
#include <stdio.h>
#include <math.h>

#define STEP 0.2
#define PREC 0.01
#define PRESNOST 0.000001

double f1(double x);
double f2(double x);
double deriv(double(*p_fn)(), double x);

int main(){
    double r1, r2, (*p_f1)(), (*p_f2)();
    p_f1 = f1;
    p_f2 = f2;
    scanf("%lf %lf", &r1, &r2);
    printf("x f1(x) f1'(x) f2(x) f2'(x)\n");
    while (r1 <= r2 + PRESNOST){
        printf("%.2lf %.2lf %.2lf %.2lf %.2lf\n", r1, f1(r1), deriv((*p_f1), r1), f2(r1), deriv((*p_f2), r1));
        r1 += STEP;
    }
    return 0;
}

double f1(double x){
    return (exp(x) / (fabs(x) + 1));
}

double f2(double x){
    return (x * sin(x));
}

double deriv(double(*p_fn)(), double x){
    return ((*p_fn)(x + PREC) - (*p_fn)(x))/PREC;
}