C++ vector::data()用法及代碼示例

C++ vector::data() 函數

vector::data() 是 "vector" 頭文件的庫函數，用於訪問向量元素，它返回一個指向向量內部用於存儲元素的內存數組的指針。

注意：要使用矢量，請包括<vector>標題。

vector::data() 函數的語法

    vector::data();

參數： none——它什麽都不接受。

返回值： value_type*– 它返回一個指向向量內部使用的數組中第一個元素的指針。

例：

    Input:
    vector<int> vector1{ 1, 2, 3, 4, 5 };
    
    //declare a pointer of same type
    int* ptr = vector1.data();
    
    Accessing elements:
    cout << *ptr << endl;
    ptr++;
    cout << *ptr << endl;

    Output:
    1
    2

C++程序演示vector::data()函數的例子

//C++ STL program to demonstrate example of
//vector::data() function

#include <iostream>
#include <vector>
using namespace std;

int main()
{
    vector<int> v1{ 10, 20, 30, 40, 50 };

    //declare a pointer of same type
    int* ptr = v1.data();

    //printing all elements
    //using vector::data() function
    cout << "all elements of vector v1..." << endl;
    for (int i = 0; i < v1.size(); i++) {
        cout << "element at index " << i << ":" << *ptr << endl;
        //increasing pointer
        ptr++;
    }

    //updating some elements
    //initializing the pointer again
    ptr = v1.data();
    *(ptr + 0) = 100;
    *(ptr + 1) = 200;
    *(ptr + 2) = 300;

    //after updating, printing all elements
    //using vector::data() function
    cout << "all elements of vector v1..." << endl;
    for (int i = 0; i < v1.size(); i++) {
        cout << "element at index " << i << ":" << *ptr << endl;
        //increasing pointer
        ptr++;
    }

    return 0;
}

輸出

all elements of vector v1...
element at index 0:10
element at index 1:20
element at index 2:30
element at index 3:40
element at index 4:50
all elements of vector v1...
element at index 0:100
element at index 1:200
element at index 2:300
element at index 3:40
element at index 4:50

參考：C++ vector::data()