C-Code

#include <stdio.h>
#include <limits.h>
#define ANZ_TARIFE 5

enum Pakete {
    PBasis = 0, P100 = 100, P300 = 300, P600 = 600, PFlat = INT_MAX
};

struct Mobilfunktarif {
    enum Pakete p;  // Paket
    double g;       // Grundpreis
    int f;          // Freiminuten
    double m;       // Minutenpreis
}t[ANZ_TARIFE];

void erstelle_tarife() {
    t[0].p = PBasis;    t[0].g = 2.95;      t[0].f = PBasis;   t[0].m = 0.10;
    t[1].p = P100;      t[1].g = 4.95;      t[1].f = P100;     t[1].m = 0.12;
    t[2].p = P300;      t[2].g = 7.95;      t[2].f = P300;     t[2].m = 0.15;
    t[3].p = P600;      t[3].g = 12.95;     t[3].f = P600;     t[3].m = 0.20;
    t[4].p = PFlat;     t[4].g = 29.95;     t[4].f = PFlat;    t[4].m = 0.00;
}

double gesamt_preis(enum Pakete paket, int minuten) {
    double g_preis = 0.0;
    for (unsigned int i = 0; i < ANZ_TARIFE; i++)
    {
        if (t[i].p == paket) {
            int rest = minuten - t[i].f;
            if (rest < 0) rest = 0;
            g_preis = rest * t[i].m + t[i].g;
            break;
        }
    }
    return g_preis;
}

void main() {
    erstelle_tarife();
    enum Pakete paket = P300;
    int minuten = 400;
    printf("Der Gesamtpreis im Monat betraegt %.2f Euro.\n", gesamt_preis(paket, minuten));
}