11個C++代碼片段助您解決日常編程問題

1. 找出向量的大小

#include 
using namespace std;
 
int main()
{
    vector <int> arr1 = {1, 2, 3, 4};
    vector <int> arr2 = {};
    vector <float> arr3 = {1.2, 3.8, 3.0, 2.7, 6.6};
 
    cout << "Size of arr1: " << arr1.size() << endl;
    cout << "Size of arr2: " << arr2.size() << endl;
    cout << "Size of arr3: " << arr3.size() << endl;
 
    return 0;
}

2. 隨機排列數(shù)組

#include 
using namespace std;
 
int main()
{
    vector <int> arr = {1, 2, 3, 4};
    unsigned seed = 0;
 
    cout << "Original array:";
 
    for (int ele: arr)
    {
        cout << ele << " ";
    }
 
    cout << endl;
 
    shuffle(arr.begin(), arr.end(), default_random_engine(seed));
 
    cout << "Shuffled array:";
 
    for (int ele: arr)
    {
        cout << ele << " ";
    }
 
    return 0;
}

3. 在 C++ 中交換兩個變量

#include 
using namespace std;
 
int main()
{
    int x = 5, y = 10;
    string str1 = "MakeUseOf", str2 = "MUO";
 
    cout << "Before Swapping: " << endl;
    cout << "x: " << x << endl;
    cout << "y: " << y << endl;
    cout << "str1: " << str1 << endl;
    cout << "str2: " << str2 << endl;
 
    swap(x, y);
    swap(str1, str2);
 
    cout << "After Swapping: " << endl;
    cout << "x: " << x << endl;
    cout << "y: " << y << endl;
    cout << "str1: " << str1 << endl;
    cout << "str2: " << str2 << endl;
 
    return 0;
}

4. 求一個數(shù)的位數(shù)之和

• 初始化一個 sum 變量來存儲結果。
• 通過對 10 執(zhí)行取模運算來找到數(shù)字的余數(shù)。
• 將余數(shù)與總和相加。
• 將數(shù)字除以 10。
• 當數(shù)字大于 10 時，從步驟 2 開始重復該過程。

#include 
using namespace std;
 
int main()
{
    int num = 4635, sum = 0, temp;
 
    while (num != 0)
    {
        temp = num%10;
        sum = sum+temp;
        num = num/10;
    }
 
    cout << "Sum: " << sum << endl;
    return 0;
}

5. 將一個向量復制到另一個向量

#include 
using namespace std;
 
void printVector(vector <int> vec)
{
    for (auto ele: vec)
    {
        cout << ele << " ";
    }
 
    cout << endl;
}
 
int main()
{
    vector <int> vec = {1, 2, 3, 4, 5};
    printVector(vec);
 
    // Method 1: Using Assignment Operator
    vector <int> newVec1 = vec;
    printVector(newVec1);
 
    // Method 2: By passing vector as constructor
    vector <int> newVec2(vec);
    printVector(newVec2);
 
    return 0;
}

6. 找出數(shù)組的最大和最小元素

#include  
using namespace std;
 
int main()
{
    int arr[] = {23, 56, 99, 15, 56};
    int size = sizeof(arr)/sizeof(arr[0]);
 
    cout << "Max element: " << *max_element(arr, arr+size) << endl;
    cout << "Min element: " << *min_element(arr, arr+size) << endl;
 
    return 0;
}

7. 在集合中插入元素

#include 
using namespace std;
 
int main()
{
    set<string> st;
 
    st.insert("Make");
    st.insert("Use");
    st.insert("Of");
    st.insert("Of");
 
    for (auto it = st.begin(); it != st.end(); it++)
    {
        cout << *it << " ";
    }
 
    return 0;
}

8.從字符串中刪除重復項

#include 
using namespace std;
 
void removeDuplicateCharacters(char str[], int size)
{
    int newIndex=0;
 
    // Traversing through all the characters
    for (int i = 0; i < size; i++)
    {
        int j;
 
        // Traversing loop from the first character to current character
        for (j = 0; j < i; j++)
        {
            if (str[i] == str[j])
            {
                break;
            }
        }
 
        if (j == i)
        {
            str[newIndex++] = str[i];
        }
    }
 
    // After removing duplicates, we make
    // the vacant part of string to null
    str[newIndex] = '?';
}


int main()
{
    char str[] = "MakeUseOf";
    int size = strlen(str);
 
    cout << "Original String: " << endl;
    cout << str << endl;
 
    removeDuplicateCharacters(str, size);
 
    cout << "New String: " << endl;
    cout << str << endl;
    return 0;
}

9. 求 C++ 字符串的長度

#include 
using namespace std;
 
int main()
{
    string str1 = "MakeUseOf";
    cout << "Length of " << str1 << " : " << str1.length() << endl;
 
    string str2 = "lorem ipsum";
    cout << "Length of " << str2 << " : " << str2.size() << endl;
 
    return 0;
}

10. 從數(shù)組中刪除一個元素

#include 
using namespace std;
 
int deleteElementFromArray(int arr[], int size, int elementToBeDeleted)
{
    int i, j;
 
    // Search if elementToBeDeleted is present
    // in the array or not
    for (i = 0; i < size; i++)
    {
        if (arr[i] == elementToBeDeleted)
        {
            break;
        }
    }
 
    // If elementToBeDeleted is found in the array
    if (i < size)
    {
        // We need to reduce the size of the array
        // and shift the rest elements
        size = size - 1;
 
        for (j = i; j < size; j++)
        {
            arr[j] = arr[j+1];
        }
    }
 
    // New array size is returned
    return size;
}
 
void printArrayElements(int arr[], int size)
{
    for (int i = 0; i < size; i++)
    {
        cout << arr[i] << " ";
    }
 
    cout << endl;
}


int main()
{
    int arr[] = {1, 2, 3, 4, 5};
    int size = sizeof(arr)/sizeof(arr[0]);
 
    cout << "Original Array: " << endl;
    printArrayElements(arr, size);
 
    int elementToBeDeleted = 3;
    size = deleteElementFromArray(arr, size, elementToBeDeleted);
 
    cout << "New array: " << endl;
    printArrayElements(arr, size);
 
    return 0;
}

11. 遍歷向量

使用范圍for(range for)

#include 
using namespace std;
 
int main()
{
    vector <int> vec = {1, 2, 3, 4, 5};
 
    // Method 1: Using range for
    for (auto element: vec)
    {
        cout << element << " ";
    }
 
    return 0;
}

使用索引

#include 
using namespace std;
 
int main()
{
    vector <int> vec = {1, 2, 3, 4, 5};
 
    // Method 2: Using indexing
    for (int i = 0; i < vec.size(); i++)
    {
        cout << vec[i] << " ";
    }
 
    return 0;
}

使用迭代器的引用

#include 
using namespace std;
 
int main()
{
    vector <int> vec = {1, 2, 3, 4, 5};
 
    // Method 3: Using reference of the iterator
    for (auto it = begin(vec); it != end(vec); it++)
    {
        cout << *it << " ";
    }
 
    return 0;
}

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