Question

我的代码是这样的我只想将我的do-while循环转换为for循环或while循环我该怎么做。程序的要点是反转输入的单词。就像你输入abc一样，它将输出为cba。

int main()
{

    while (i < --length - 1);
        cout << word << endl;
return 0;
}

Answer 1

将while循环转换为for循环的传统方法采用以下形式：

// While loop
int i = 0;
while( i < n ) {
    // Amazing things happen here
    i++;
}

// Equivalent for loop
for( int i = 0; i < n; i++ ) {
    // Amazing things still happen here
}

因此，应用于您的代码看起来像：

char ch = word[i];
word[i] = word[length - 1];
word[length - 1] = ch;

for( int i = 0, length = word.length(); i < --length - 1; i++ ) {
    char ch = word[i];
    word[i] = word[length - 1];
    word[length - 1] = ch;
}

请注意，由于do-while循环在测试之前执行循环体，我不得不将循环体的一个副本放在前面。为了避免必须更新代码的两个不同副本，您可能需要将循环体提取到函数中，然后在循环前和循环体中调用该函数。

对于while循环版本：

int i = 0, length = word.length();

char ch = word[i];
word[i] = word[length - 1];
word[length - 1] = ch;

while( ++i < --length ) {
    char ch = word[i];
    word[i] = word[length - 1];
    word[length - 1] = ch;
}

Answer 2

另一种选择是，它不会对0或1大小的字符串做任何事情：

int length = word.length();
if (length > 1)
{
    int i = 0;
    char ch;
    while (i < length)
    {
        ch = word[i];
        word[i] = word[length - 1];
        word[length - 1] = ch;
        i++;
        length--;
    }
}

对于版本：

int length = word.length();
if (length > 1)
{
    char ch;
    for(int i = 0; i < length; i++, length--)
    {
        ch = word[i];
        word[i] = word[length - 1];
        word[length - 1] = ch;
    }
}

将do-while循环转换为while循环

2 个答案: