定义变量的地方！

这使得它似乎有点更清楚，价值5是只被分配到变量B。

Because defining multiple variables on a single line AND initializing them is a recipe for mistakes, we recommend that you only define multiple variables on a line if you’re not initializing any of them.

因为定义多个变量在一个单一的线和初始化是一方的错误，我们建议您只定义多个变量对线如果你没有初始化任何人。

Rule: Avoid defining multiple variables on a single line if initializing any of them.

规则：避免定义多个变量在一个单一的线如果初始化任何人。

Where to define variables

定义变量的地方

Older C compilers forced users to define all of the variables in a function at the top of the function:

老年编译器强制用户定义函数中的所有变量的函数的顶部的功能：

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int main()
{
    // all variable up top
    int x;
    int y;
 
    // then code
    using namespace std;
    cout << "Enter a number: ";
    cin >> x;
 
    cout << "Enter another number: ";
    cin >> y;
 
    cout << "The sum is: " << x + y << endl;
    return 0;
}

这种风格现在已经过时。编译器不需要在函数的顶部定义所有变量。适当的+ +的风格是将变量定义为可能的变量，尽可能靠近第一次使用这个变量：

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int main()
{
    using namespace std;
 
    cout << "Enter a number: ";
    int x; // we need x on the next line, so we'll declare it here, as close to its first use as possible.
    cin >> x; // first use of x
 
    cout << "Enter another number: ";
    int y; // we don't need y until now, so it gets declared here
    cin >> y; // first use of y
 
    cout << "The sum is: " << x + y << endl;
    return 0;
}