CookingC++

把一个array拷贝到vector

其中的copy方法里，copy(&dataArray[0], &dataArray[dataArraySize], back_inserter(dataVec)); 不会拷贝dataArray[dataArraySize] 元素；例子如下：

int arr[] = {1,4,2,4,56,5,43,2,2,5};
int main()
{
    int size = sizeof(arr) / sizeof(int);
    vector<int> table;
    copy(&arr[0], &arr[3], back_inserter(table));
    for (auto  i : table)
        cout << i << " ";
    cout << endl;
}
//打印到arr[2]处为止；
$main
1 4 2

vector<int> dataVec;

int dataArray[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
unsigned dataArraySize = sizeof(dataArray) / sizeof(int);

// Method 1: Copy the array to the vector using back_inserter.
{
    copy(&dataArray[0], &dataArray[dataArraySize], back_inserter(dataVec));
}

// Method 2: Same as 1 but pre-extend the vector by the size of the array using reserve
{
    dataVec.reserve(dataVec.size() + dataArraySize);
    copy(&dataArray[0], &dataArray[dataArraySize], back_inserter(dataVec));
}

// Method 3: Memcpy
{
    dataVec.resize(dataVec.size() + dataArraySize);
    memcpy(&dataVec[dataVec.size() - dataArraySize], &dataArray[0], dataArraySize * sizeof(int));
}

// Method 4: vector::insert
{
    dataVec.insert(dataVec.end(), &dataArray[0], &dataArray[dataArraySize]);
}

// Method 5: vector + vector
{
    vector<int> dataVec2(&dataArray[0], &dataArray[dataArraySize]);
    dataVec.insert(dataVec.end(), dataVec2.begin(), dataVec2.end());
}

按符号切割字符串

std::string s = "scott>=tiger";
std::string delimiter = ">=";
std::string token = s.substr(0, s.find(delimiter)); // token is "scott"

• The find(const string& str, size_t pos = 0) function returns the position of the first occurrence of str in the string, or npos if the string is not found.
• The substr(size_t pos = 0, size_t n = npos) function returns a substring of the object, starting at position pos and of length npos.

删除字符串中的空白符号

s.erase(remove_if(s.begin(), s.end(),::isspace), s.end());