make_pair() andp air and function fflush()

function name: fflush(FILE *stream)
function: clear the read and write buffer, you need to immediately write the output buffer data into the specified stream;
head file: stdio.h
prototype: int fflush(FILE *stream)
the "stream" is the stream to be washed

make_pair() andp air
std::pair the main purpose is to combine two data into a single data, the two data can be the same type of different types, such as std::pair<int, float> or std::pair<double, double>, and so on. A pair is essentially a structure whose main two member variables are first and second, and these two variables can be used directly. initialize a pair you can use the constructor, or you can use the std::make_pair function. the make_pair function is defined as follows:
template pair make_pair(T1 a, T2 b) {return pair(a ,b);}
general make_pair are used in the position where need to pair to be the parameters, you can directly call make_pair generated pair object, another usage is that the pair can accept implicit conversions which gives greater flexibility, but this will be the following questions: For example, the following two definitions:
std::pair<int>(1,1.1);

std::make_pair(1, 1.1);
where the first second variable is a float type, and the make_pair function converts the second variable to a double type, this problem in programing is the need to draw attention

std::pair主要的作用是将两个数据组合成一个数据，两个数据可以是同一类型或者不同类型。例如std::pair<int,float> 或者 std：：pair<double,double>等。pair实质上是一个结构体，其主要的两个成员变量是first和second，这两个变量可以直接使用。初始化一个pair可以使用构造函数，也可以使用std::make_pair函数，make_pair函数的定义如下：
template pair make_pair(T1 a, T2 b) { return pair(a, b); }
一般make_pair都使用在需要pair做参数的位置，可以直接调用make_pair生成pair对象。 另一个使用的方面就是pair可以接受隐式的类型转换，这样可以获得更高的灵活度。但是这样会出现如下问题：例如有如下两个定义：
std::pair<int, float>(1, 1.1);

std::make_pair(1, 1.1);
其中第一个的second变量是float类型，而make_pair函数会将second变量都转换成double类型。这个问题在编程是需要引起注意。下面是一段pair与make_pair的例子程序：