#include<iostream>
using namespace std;
void TestFunc(int a = 0)//參數(shù)缺省值
{
	cout << a << endl;
}
int main()
{
	TestFunc();//沒有指定實(shí)參，使用缺省值
	TestFunc(10);//指定實(shí)參，使用實(shí)參
	return 0;
}

#include<iostream>
using namespace std;
namespace WD
{
	struct Stack
	{
		int* a;
		int size;
		int capacity;	
	};
}
using namespace WD;
void StackInit(struct Stack* ps)
{
	ps->a = NULL; 
	ps->capacity = 0;
	ps->size = 0;
}
void StackPush(struct Stack* ps, int x)
{
	if(ps->size == ps->capacity)
	{
		//ps->capacity *= 2;//err
		ps->capacity == 0 ? 4 : ps->capacity * 2;//這里就必須寫一個(gè)三目
	}
}
void StackInitCpp1(struct Stack* ps, int defaultCP)
{
	ps->a = (int*)malloc(sizeof(int) * defaultCP);
	ps->capacity = 0;
	ps->size = defaultCP;
}
void StackInitCpp2(struct Stack* ps, int defaultCP = 4)//ok
{
	ps->a = (int*)malloc(sizeof(int) * defaultCP);
	ps->capacity = 0;
	ps->size = defaultCP;
}
int main()
{
	//假設(shè)明確知道這里至少需要100個(gè)數(shù)據(jù)到st1
	struct Stack st1; 
	StackInitCpp1(&st1, 100);
	//假設(shè)不知道st2里需要多少個(gè)數(shù)據(jù) ———— 希望開小點(diǎn)
	struct Stack st2;  
	StackInitCpp2(&st1);//缺省
	return 0;
}

void TestFunc(int a = 10, int b = 20, int c = 30)
{
	cout << "a = " << a << endl;
	cout << "b = " << b << endl;
	cout << "c = " << c << endl;
	cout << endl;
}
int main()
{
	//非常靈活，
	TestFunc();
	TestFunc(1);
	TestFunc(1, 2);
	TestFunc(1, 2, 3);	
	//TestFunc(1, , 3);//err，注意它沒辦法實(shí)現(xiàn)b不傳，只傳a和b，也就是說編譯器只能按照順序傳
	return 0;
}

//void TestFunc(int a, int b = 10, /*int f, - err*/ int c = 20);//err，void TestFunc(int a, int b = 10, /*int f, int x = y, -> err*/ int c = 20){cout << "a = " << a << endl;cout << "b = " << b << endl;cout << "c = " << c << endl;cout << endl;}int main(){//TestFunc();//err，至少得傳一個(gè)，這是根據(jù)形參有幾個(gè)非半缺省參數(shù)確定的TestFunc(1);TestFunc(1, 2);TestFunc(1, 2, 3);return 0;}//void TestFunc(int a, int b = 10, /*int f, - err*/ int c = 20);//err，
void TestFunc(int a, int b = 10, /*int f, int x = y, -> err*/ int c = 20)
{
	cout << "a = " << a << endl;
	cout << "b = " << b << endl;
	cout << "c = " << c << endl;
	cout << endl;
}
int main()
{
	//TestFunc();//err，至少得傳一個(gè)，這是根據(jù)形參有幾個(gè)非半缺省參數(shù)確定的
	TestFunc(1);
	TestFunc(1, 2);
	TestFunc(1, 2, 3);	
	return 0;
}

//a.hvoid TestFunc(int a = 10);//a.cppvoid TestFunc(int a = 20){}