// 变量声明在for里面，自增在里面
for (int i = 0; i < 10; ++i) {
	//...
}

// 变量声明在外面,自增在里面
int i = 0;
for (; i < 10; ) {
	//...
	++i;
}

bool condition = true;
int i = 0;
for (; condition; ) {
	//...
	++i;
	if (!(i < 5))
		condition = false;
}

bool condition = true;
int i = 0;
for (; ; ) {
	//...
	++i;
	if (!(i < 5))
		condition = false;
}

std::vector<int> l{1,2,3,4,5,6,7,8,9};
for (const auto& it : l) {
	std::cout << it << std::endl;
}

int i = 0;
do {
	++i;
} while ( i < 5 )

do {

} while ( false )