Question

    srand(time(NULL));
    int rand = Randomiser();
    temp = placement[49];
    //Loops variables in array to produce scrolling
    for(i = 0;i<50; i++)
    {
        placement[49-i] = placement[49-(i+1)];
    }
    if(temp==2)
    {
        temp=temp2;
    }
    if(rand>90)
    {
      temp2=temp;
      temp=2;
    }
    placement[0]=temp;

所以我把它改成了这样的东西，现在插入了我的值，但问题是这个值一次插入大约12次。所以6个位置= 2

Answer 1

它不会忽略if语句，它只是在内部for循环的第一次迭代后才计算为false。你的代码：

for( ... )
{
    bool controlRod = true;
    for( ... )
    {
        if( ... && controlRod == true )
        {
               // ...
        }
        // ...
        controlRod = false; // <-- set to false so condition is always false
    }
}

如果我们展开内循环，我们得到类似的东西：

for( ... )
{
    bool controlRod = true;

    // iteration 1 ----------------------------------------------------
    if( ... && controlRod == true )
    {
        // ...
    }
    // ...
    controlRod = false; // <-- set to false so condition is always false

    // iteration 2 ------------------------------------------------------
    if( ... && controlRod == true ) // controlRod was set to false, 
                                    // so this will never be true
    {
        // ...
    }
    // ...
    controlRod = false; // <-- set to false so condition is always false

    // iteration 3 --------------------------------------------------
    if( ... && controlRod == true ) // controlRod was set to false, 
                                    // so this will never be true
    {
        // ...
    }
    // ...
    controlRod = false; // <-- set to false so condition is always false

    // more iterations...
}

Answer 2

以下代码是您真正想要的吗？在这个例子中，i-loop旋转环。请注意，通常您不会移动所有元素，只需通过(start+i)%size移动环开始和地址。

注意，对于排序，您有std::sort，这比冒泡排序更有效。

#include <cstdlib>
#include <vector>
#include <iostream>

int Randomiser() {
    return rand() % 101;
}

int main() {
    srand(time(NULL));
    std::vector<int> placement(50,0);

    for(int j = 0; j<100; j++)
    {
        int temp, temp2;
        int rand = Randomiser();
        bool controlRod=true;
        if(rand<80)
        {
            temp2 = placement[49];
            placement[49]=2;
        } 
        temp = placement[49];
        for(int i = 0; i<50; i++)
        {
            placement[49-i] = placement[49-(i+1)];
        }
        placement[0] = temp;
    }

    std::cout << "\nThis time in placement[0]: " << placement[0] << "\n";
}
/**
     Local Variables:
     compile-command: "g++ -g test.cc -o test.exe; ./test.exe"
     End:
*/

忽略if语句用于冒泡排序

2 个答案: