c++ function vector passing parameters

A vector is different from an array. The array itself is similar to a pointer, so what is passed in is a pointer. But vector is not so

Three ways of vector parameter passing:

• void func1(vector vet); //Transfer value
• void func2(vector &vet); //reference
• void func3(vector *vet); //Pointer

The effects of these three methods:

• Call the copy constructor, the formal parameter changes will not affect the actual parameters
• Do not call the copy constructor, the formal parameter changes affect the actual parameters
• Do not call the copy constructor, the formal parameter changes affect the actual parameters

code show as below:

void func1(vector<int> vet) {
    
    
	vet.emplace_back(1);
}
void func2(vector<int>  &vet) {
    
    
	vet.emplace_back(2);
}
void func3(vector<int>  *vet) {
    
    
	vet->emplace_back(3);	//指针用 ->
}
int main() {
    
    
	vector<int> vet;
	func1(vet);
	cout << vet[0] << endl;	//!!!报错，因为实参不会改变（想正常运行可注释掉这句）

	vector<int> vet2;
	func2(vet2);
	cout << vet2[0] << endl;	//输出 2

	vector<int> vet3;
	func3(&vet3);	//这里取得是指针
	cout << vet3[0] << endl;	//输出 3
	//system("pause");
	return 0;
}

end:

vector best use references or pointers of mass participation , because if the large amount of data when the copy will be very slow; If you just do not want data to be modified, can be added before the vector const .