Question

我想要的是让用户猜测数字的次数，然后告诉他猜测它的次数，这就是为什么我要为for loop g！= r，但是，我不知道C ++是否允许这样做。

此外，我在尝试编译时遇到的错误是

expression must have a constant value 

expression did not evaluate to a constant" and "case expression not constant

这是代码：

int main()
{
    int r = rand() % 101;
    int g = 0;
    int t = 10;

    std::cout << "Guess a number, human (From 1 to 100)." << std::endl;
    std::cin >> g;

    for (int t = 0; g != r; t++)
    {
        switch (g) {
        case (g == r):
            std::cout << "You won, now get lost!" << std::endl;
            break;
        case (g < r):
            std::cout << "Too low, piece of turd." << std::endl;
            break;
        case (g > r):
            std::cout << "Too high, dubai." << std::endl;
            break;
        default :
            std::cout << "How could you possibly have gotten it wrong, you stupid ape." << std::endl;
        }
    }
    std::cout << "Finally!, it took you " << t << " freaking times!" << std::endl;


    return 0;
}

Answer 1

切换案例检查必须是常量表达式，与原始值进行相等性比较。

在您的情况下，您可以使用 if 命令重写开关。使用下面的代码，它将编译。

if (g == r)
{
    std::cout << "You won, now get lost!" << std::endl;
}
else if (g < r)
{
    std::cout << "Too low, piece of turd." << std::endl;
}
else if (g > r)
{
    std::cout << "Too high, dubai." << std::endl;
} 
else 
{
    // will not get here, as previous if already cover all cases
    std::cout << "How could you possibly have gotten it wrong, you stupid ape." << std::endl;
}

C ++开关 http://en.cppreference.com/w/cpp/language/switch

C ++ if http://en.cppreference.com/w/cpp/language/if

Answer 2

如果您需要使用交换机，您可以尝试在切换之前使用带有标志的while循环和一些检查：

bool flag = true;
int t = 0;
int x = 0;
while( flag )
{
        t++;
        std::cout << "Guess a number, human (From 1 to 100)." << std::endl;
        std::cin >> g;

        if( g == r )
        {
           x = 1;
           flag = false;
        }
        else if( g < r )
           x = 2;
        else
           x = 3;

        switch (x) {
        case (1):
            std::cout << "You won, now get lost!" << std::endl;
            break;
        case (2):
            std::cout << "Too low, piece of turd." << std::endl;
            break;
        case (3):
            std::cout << "Too high, dubai." << std::endl;
            break;
        default :
            std::cout << "How could you possibly have gotten it wrong, you stupid ape." << std::endl;
        }
}

Answer 3

我将其更改为 if 语句，现在在第一次猜测之后，用户无法再次猜测。

好的，这里有新代码：

int main（）

{

<!DOCTYPE html>
<html>
<head>

<script>
function loadList() {
  var xhttp;    
  var x = document.getElementById("x").value;
  var y = document.getElementById("y").value;
  xhttp = new XMLHttpRequest();
  xhttp.onreadystatechange = function() {
    if (xhttp.readyState == 4 && xhttp.status == 200) {
      document.getElementById("table").innerHTML = xhttp.responseText;
    }
  };
  xhttp.open("GET", "list.php?x="+x+"&y="+y, true);
  xhttp.send();
}
</script>

</head>
<body>

<form action="">
    <input type="text" id="x"> <br> 
    <input type="text" id="y"> <br>
    <input type="button" value="Find" onclick="loadList()">
</form>

<div id="table"> </div>

</body>
</html>

}

我的switch语句不允许我使用特定变量作为表达式

3 个答案: