Call by Value vs Call by Reference

Call by Value vs. Call by Reference in C

Feature	Call by Value	Call by Reference (nur über Zeiger)
Übergebenes Argument	Kopie des Wertes	Adresse der Variable
Effekt auf Original	Keine Änderung am Original	Original kann verändert werden
Speicherverbrauch	Mehr (jede Kopie braucht Speicher)	Weniger (nur Adresse wird übergeben)
Sicherheit	Sicher, keine externen Änderungen	Vorsicht, da Original geändert werden kann

• Hinweis: C unterstützt kein echtes Call by Reference. Änderungen am Original sind nur möglich, indem man einen Zeiger (Pointer) auf die Variable übergibt.

Beispiele

Call by Value

#include <stdio.h>
void modifyValue(int x) {
    x = 20;  // Ändert nur die Kopie, Original bleibt unverändert
}
int main() {
    int a = 10;
    modifyValue(a);
    printf("Wert von a: %d\n", a);  // Ausgabe: 10
    return 0;
}

Call by Reference (über Zeiger)

#include <stdio.h>
void modifyValue(int *x) {
    *x = 20;  // Ändert das Original durch den Zeiger
}
int main() {
    int a = 10;
    modifyValue(&a);
    printf("Wert von a: %d\n", a);  // Ausgabe: 20
    return 0;
}

• Call by Value: Funktion arbeitet mit einer Kopie; keine Änderung am Original.
• Call by Reference (über Zeiger): Funktion arbeitet mit einer Adresse; erlaubt Änderung am Original.

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