C++_STL_常用的拷贝和替换算法

客官°小女子只卖身不卖艺 2021-12-12 06:15 192阅读 0赞

## copy() ##

**把A数组拷贝到另一个B数组中。**

void main_copy()
    {
    	vector<int> vecIntA;
    	vecIntA.push_back(1);
    	vecIntA.push_back(3);
    	vecIntA.push_back(5);
    	vecIntA.push_back(7);
    	vecIntA.push_back(9);
    	vector<int> vecIntB;
    	vecIntB.resize(5);			//扩大空间
    	copy(vecIntA.begin(), vecIntA.end(), vecIntB.begin());	//vecIntB: {1,3,5,7,9}
    	cout << "拷贝之后的B为" << endl;
    	printV(vecIntB);
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzkxNjc1NQ_size_16_color_FFFFFF_t_70]

## replace() ##

replace(beg,end,oldValue,newValue):    将指定范围内的所有等于oldValue的元素替换成newValue。
    		vector<int> vecIntA;
    		vecIntA.push_back(1);
    		vecIntA.push_back(3);
    		vecIntA.push_back(5);
    		vecIntA.push_back(3);
    		vecIntA.push_back(9);
    		replace(vecIntA.begin(), vecIntA.end(), 3, 8);		//{1,8,5,8,9}
    void main_replace()
    {
    	vector<int> v1;
    	v1.push_back(1);
    	v1.push_back(3);
    	v1.push_back(5);
    	v1.push_back(7);
    	cout << "替换前" << endl;
    	printV(v1);
    	replace(v1.begin(), v1.end(), 3, 5);
    	cout << "把3替换5之后" << endl;
    	printV(v1);
    }

![在这里插入图片描述][201907101355213.png]

## Replace\_if() ##

bool great_equal_5(int n)
    {
    	if (n > 5)
    	{
    		return n;
    	}
    	else
    		return false;
    }
    void main_replaceif() //把所有大于等于5的都变成0
    {
    	vector<int> v1;
    	v1.push_back(1);
    	v1.push_back(3);
    	v1.push_back(5);
    	v1.push_back(7);
    	cout << "替换前" << endl;
    	printV(v1);
    	// 
    	replace_if(v1.begin(), v1.end(), great_equal_5, 0);
    	cout << "把3替换5之后" << endl;
    	printV(v1);

![在这里插入图片描述][20190710135557203.png]

## Swap() ##

**两个数组交换**

void main_swap()
        {
        	vector<int> v1;
        	v1.push_back(1);
        	v1.push_back(2);
        	v1.push_back(4);
        	vector<int> v2;
        	v2.push_back(3);
        	swap(v1, v2);
        	cout << "A和B交换之后,B变成了:" << endl;
        	printV(v2);
        }

![在这里插入图片描述][20190710135630628.png]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzkxNjc1NQ_size_16_color_FFFFFF_t_70]: /images/20211211/103dff9f73a946db849c96251f5d1490.png
[201907101355213.png]: /images/20211211/77e86343e2dc4622b022facc3cdab0af.png
[20190710135557203.png]: /images/20211211/cd54b167ed354b578213be4fb4137b80.png
[20190710135630628.png]: /images/20211211/b52186a703594f30b10ecf1d0c760ba5.png