Archief - [PROG][C++] Typecasting, tijdelijke variabelen en call by (constant) reference

Actual arguments must be type-compatible with the formal arguments, without the use of a typecast. This is required because a typecast generates a temporary variable and that temporary variable would become the actual argument. Then changes to the formal parameter in the invoked function would change the temporary variable (instead of the original), leading to hard-to-find bugs.

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#include <iostream>
using namespace std;

class Persoon {
	public:
		Persoon(const string &n): naam(n) {
		}
		
		string naam;
};

class Student: public Persoon {
	public:
		Student(const string &n): Persoon(n) {
		}
};

void veranderNaam(Persoon &p, const string &n) {
	p.naam = n;
}

int main() {
	Student s("Fred");
	veranderNaam((Persoon)s, "Mark");

	cout << "Naam: " << s.naam << endl;

	return EXIT_SUCCESS;
}

../main.cpp: In function `int main()':
../main.cpp:24: error: invalid initialization of non-const reference of type 'Persoon&' from a temporary of type 'Persoon'
../main.cpp:18: error: in passing argument 1 of `void veranderNaam(Persoon&, const std:tring&)'
mingw32-make.exe: *** [main.o] Error 1

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