c++中stl 哈希函数_C ++ STL中的set :: emplace（）函数

今天药忘吃喽~ 2023-03-05 12:48 16阅读 0赞

c++中stl 哈希函数

## C ++ STL set :: emplace()函数 **(**C++ STL set::emplace() function**)** ##

**set::emplace() function** is a predefined function, it is used to insert a new element to the set, if element is unique.

**set :: emplace()函数**是预定义的函数，如果element是唯一的，则用于将新元素插入集合。

**Prototype:**

**原型：**

set<T> st; //declaration
        st.emplace(T item);

**Parameter:** T item; //T is the data type

**参数：** T项； // T是数据类型

**Return type:** If it successfully inserts then it returns a pair<Iterator pointer to the inserted value, True&gt, Else It returns a pair<iterator to the existing value in the set, False>

**返回类型：**如果成功插入，则返回对<迭代器指针，指向插入的值True＆gt ，否则返回对<迭代器 ，返回集合中的现有值False>

**Usage:** The function inserts unique elements to the set.

**用法：**该函数在集合中插入唯一元素。

**Example:**

**例：**

For a set of integer,
        set<int> st;
        st.emplace(5);
        st.emplace(4);
        set content: //sorted always(ordered)
            4
            5
    
        st.emplace(5) //no insertion this time
        set content: 
            4
            5

**Header file to be included:**

**包含的头文件：**

#include <iostream>
        #include <set>
        OR
        #include <bits/stdc++.h>

**C++ implementation:**

**C ++实现：**

#include <bits/stdc++.h>
    using namespace std;
    
    void printSet(set<int> st){
        
    	set<int>:: iterator it;
    	cout<<"Set contents are:\n";
    	if(st.empty()){
        
    		cout<<"empty set\n";
    		return;
    	}
    	for(it=st.begin();it!=st.end();it++)
    		cout<<*it<<" ";
    	cout<<endl;
    }
    
    int main(){
        
    	cout<<"Example of emplace function\n";
    	set<int> st;
    	set<int>:: iterator it;
    	cout<<"inserting 4\n";
    	st.emplace(4);
    	cout<<"inserting 6\n";
    	st.emplace(6);
    	cout<<"inserting 10\n";
    	st.emplace(10);
    
    	printSet(st); //printing current set
    	
    	return 0;
    }

**Output**

**输出量**

Example of emplace function
    inserting 4
    inserting 6
    inserting 10
    Set contents are:
    4 6 10

> 翻译自: [https://www.includehelp.com/stl/set-emplace-function-in-cpp-stl.aspx][https_www.includehelp.com_stl_set-emplace-function-in-cpp-stl.aspx]

c++中stl 哈希函数

[https_www.includehelp.com_stl_set-emplace-function-in-cpp-stl.aspx]: https://www.includehelp.com/stl/set-emplace-function-in-cpp-stl.aspx