通過代碼實(shí)例解析c++ vector常用方法
1. c++ vector 每個(gè)元素加上一個(gè)特定值 (c++ vector add a constant value for each element)
https://stackoverflow.com/questions/4461446/stl-way-to-add-a-constant-value-to-a-stdvector
vector<int> x = {0, 30, 80, 100, 120, 150, 190, 220, 250}; //transform可以將函數(shù)應(yīng)用到序列的元素上,bind2nd通過綁定其中一個(gè)參數(shù)把二元函數(shù)轉(zhuǎn)換成一元函數(shù) transform(x.begin(), x.end(), x.begin(), bind2nd(plus<int>(), 1)); //顯示x的值 copy(x.begin(), x.end(), ostream_iterator<int>(cout, " "));
結(jié)果: x = {1 31 81 101 121 151 191 221 251}
2. c++判斷vector中是否存在某個(gè)元素(c++ judge whether an element exists in the vector)
https://www.techiedelight.com/check-vector-contains-given-element-cpp/
#include <iostream> #include <vector> #include <algorithm> int main() { std::vector<int> v = { 4, 7, 5, 2, 6, 9 }; int key = 6; if (std::count(v.begin(), v.end(), key)) std::cout << "Element found"; else std::cout << "Element not found"; return 0; }
結(jié)果顯示:Element found
3. c++ vector<int> 生成指定個(gè)數(shù)的順序列表 (c++ generate a sequential vector<int> of special numbers)
https://stackoverflow.com/questions/17694579/use-stdfill-to-populate-vector-with-increasing-numbers
std::vector<int> seq(10);
// 定義在 numeric 頭文件中的 iota() 函數(shù)模板會(huì)用連續(xù)的 T 類型值填充序列
std::iota(seq.begin(), seq.end(), 0);
結(jié)果: seq = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
4. c++ 一條語(yǔ)句打印vector信息(c++ print out vector by one statement).
https://stackoverflow.com/questions/10750057/how-to-print-out-the-contents-of-a-vector
vector<int> x = {1, 2, 3, 4};
//istream_iterator用于從輸入流中讀取連續(xù)的元素
copy(x.begin(), x.end(), ostream_iterator<int>(cout, " "));
結(jié)果顯示: 1 2 3 4
5. c++ 得到vector<int>中元素的最大值和最小值以及最大值和最小值的索引位置 (c++ get the maximum and minimum values of the elements in vector<int> and the index positions )
vector<int> row_y = { 502, 263, 684, 324, 979 }; // 最大值索引和最大值 int row_y_max_index = max_element(row_y.begin(), row_y.end()) - row_y.begin(); cout << "row_y_max_index = " << row_y_max_index << endl; int row_y_max_value = *max_element(row_y.begin(), row_y.end()); cout << "row_y_max_value = " << row_y_max_value << endl; // 最小值索引和最小值 int row_y_min_index = min_element(row_y.begin(), row_y.end()) - row_y.begin(); cout << "row_y_min_index = " << row_y_min_index << endl; int row_y_min_value = *min_element(row_y.begin(), row_y.end()); cout << "row_y_min_value = " << row_y_min_value << endl;
結(jié)果返回:
row_y_max_index = 4
row_y_max_value = 979
row_y_min_index = 1
row_y_min_value = 263
6. c++ vector 相加兩個(gè)vector (c++ append a vector to vector)
https://stackoverflow.com/questions/2551775/appending-a-vector-to-a-vector
vector<int> x = {0, 30, 80, 100, 120, 150, 190, 220, 250};
vector<int> y = {100};
y.insert(y.end(), x.begin(), x.end());
結(jié)果:y = {100, 0, 30, 80, 100, 120, 150, 190, 220, 250}
7. c++ 復(fù)制vector(c++ copy vector)
https://www.geeksforgeeks.org/ways-copy-vector-c/
vector<int> x = {0, 30, 80, 100, 120, 150, 190, 220, 250};
vector<int> y;
y.assign(x.begin(), x.end());
結(jié)果:y = {0, 30, 80, 100, 120, 150, 190, 220, 250}
8. c++ vector 根據(jù)給定索引刪除元素(c++ vector delete element based on a given index)
https://iq.opengenus.org/ways-to-remove-elements-from-vector-cpp/
若想要?jiǎng)h除第2個(gè)索引值和到第5個(gè)索引值,則可以使用下以語(yǔ)句:
vector<int> x = {0, 30, 80, 150, 120, 150, 30, 220, 80};
//remove(x.begin(), x.end(), 80);
x.erase(x.begin() + 2, x.begin() + 5 + 1);
結(jié)果: x = {0, 30, 30, 220, 80}
9. c++ 刪除vector所有指定元素(c++ delete all specified elements in the vector)
https://www.techiedelight.com/erase-elements-vector-cpp/
vector<int> x = {0, 30, 150, 30, 220, 80};
//vector中的remove的作用是將等于value的元素放到vector的尾部,但并不減少vector的size
//vector中erase的作用是刪除掉某個(gè)位置position或一段區(qū)域(begin, end)中的元素,減少其size
x.erase(remove(x.begin(), x.end(), 30), x.end());
結(jié)果: x = {0 150 220 80}
10. c++ 統(tǒng)計(jì) vector 某個(gè)元素出現(xiàn)的次數(shù) (C++ count the number of occurrences of an element in vector)
https://www.geeksforgeeks.org/std-count-cpp-stl/
vector<int> x = { 0, 3, 5, 6, 3, 2, 3 };
int n = count(x.begin(), x.end(), 3);
結(jié)果:n = 3
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