Question

这是我的C ++作业问题：

以下算法是使用嵌套循环显示菱形图案的问题的解决方案。将下面的算法转换为C ++程序。构建，运行和测试程序。

算法解决方案：

开始

Declare numRows as constant integer = 7
Declare maxPlus as constant integer = 7
Declare numSpaces as integer
Declare numPluses as integer
Declare row as integer
Declare space as integer
Declare plus as integer

Set row = 1

Repeat while row >= 1 AND row <= numRows
    Set numPluses = 2 * row - 1
    if(numPluses > maxPlus) then
        Set numPluses = 14 - numPluses
    endif

    Set numSpaces = (maxPlus - numPluses) / 2

    Set space = 1
    Repeat while space >= 1 AND space <= numSpaces
        Display( ' ')
        Set space = space + 1
    End Repeat

    Set plus = 1
    Repeat while plus >= 1 AND plus <= numPluses
        Display( '*')
        Set plus = plus + 1
    End Repeat  

    Set row = row + 1

    Display a new line
End Repeat

停止

我的代码：

   #include <iostream>
   using namespace std;

   int main() {

    const int numRows = 7;
    const int maxPlus = 7;
    int numSpaces;
    int numPluses;
    int row;
    int space;
    int plus;

    row = 1;

    while((row >=1) && (row <= numRows)){
        numPluses = 2 * row - 1;
        if(numPluses > maxPlus){
            numPluses = 14 - numPluses;
        }
        numSpaces = (maxPlus - numPluses)/ 2;
        space = 1;
        while((space >= 1) && (space <= numSpaces)){
           cout << " ";
           space++;
        }
        while((plus >= 1) && (plus <= numPluses)){
            cout << "*";
            plus++;
        }
        row++;
        cout << endl;
    }

    return 0;
    }

我的问题是为什么我没有获得钻石图案？我觉得我正确地翻译了算法，但我得到的只是一堆空白。我是否错误地阅读了问题或者我的代码是错误的？ screenshot of C++ code

Answer 1

在最后一次while循环之前：

Set plus = 1

你在翻译中错过了。

Answer 2

代码未初始化plus。

有一种习惯可以挽救很多悲伤。永远不要声明变量而不在定义点给它一个有意义的初始值。将变量的范围限制在实际使用的位置。翻译伪代码时，这意味着可以进行一些重写。 Diggit。

int main() {
    const int numRows = 7;
    const int maxPlus = 7;
    for (int row = 1; row <= numRows; ++row) {
        const int trianglePluses = 2 * row - 1;
        const int numPluses = trianglePluses <= maxPlus 
            ? trianglePluses 
            : 2 * numRows - trianglePluses;
        const int numSpaces = (maxPlus - numPluses) / 2;
        for(int space=1; space <= numSpaces; ++space) {
            cout << " ";
        }
        for (int plus = 1; plus <= numPluses; ++plus) {
            cout << "*";
        }
        cout << endl;
    }
    return 0;
}

嵌套循环菱形图案的C ++翻译算法

2 个答案: