Question

我有一个完整的工作程序，但是在我试图让程序按照我想要的方式进行操作之后，我对几个条件语句中的逻辑感到非常困惑。

    while (col < 5 || 20 < col || Number.isInteger(col)) {
        col = prompt("Columns (Int between 5 and 20): ","10");
        console.log("col " + col);
    }
    while (row < 5 || 20 < row || Number.isInteger(row)) {
        row = prompt("Rows (Int between 5 and 20): ","10");
        console.log("row " + row);
    }

    if (row>col) {size = 400/col;console.log("colmore");}
    else if (col>row) {size = 400/row;console.log("rowmore");}
    else {size = 400/col;console.log("same");}
    console.log("size " + size);

现在我的程序会提示输入Columns的数量，然后显示Rows的数量。例如，我将为列添加20，为行添加5 - 列显然比行更多。所以这发生了：

col 20
row 5
colmore
size 20

显然，这就是我想要它做的事情，但我因为第一个条件而被挂断了

if (row>col)

应该表示行是否超过列，并且程序应该继续下一个语句......或者我只是完全失去理智......？

Answer 1

我会尝试这样的事情：

while (col < 5 || col > 20 || !Number.isInteger(col)) {
    col = Number(prompt("Columns (Int between 5 and 20): ","10"));
    console.log("col " + col);
}

while (row < 5 || row > 20 || !Number.isInteger(row)) {
    row = Number(prompt("Rows (Int between 5 and 20): ","10"));
    console.log("row " + row);
}

的变化：

将字符串输入转换为数字，以便在Number（）调用中包装提示响应;这会将字符串转换为返回数字的数字，如果不是数字，则返回NaN
如果它不是一个整数（如果它是一个整数），则保持在while循环中;注意！
在while中切换第二个条件，使其更自然地读取（可能是味道问题，但我发现更容易阅读col＆lt; 5或col＆gt; 20而不是col＆lt; 5或20＆lt; col）

Answer 2

使用if（row＆gt; col）表示如果rows number（int）大于col number（int），则运行此代码

size = 400/col;console.log("colmore");

并跳过此代码

else if (col>row) {size = 400/row;console.log("rowmore");}
else {size = 400/col;console.log("same");}

然后运行此代码

console.log("size " + size);

我已经编辑了您的代码并分解了帮助您的步骤。

//declare variable as prompt first
var col = prompt("Columns (Int between 5 and 20): ","10");
/* ** continue to display prompt if user enters a number below 5 or a number above 20 or a character which is not a number ** */
while (col < 5 || col < 20 || isNaN(col)) {
  col = prompt("Columns (Int between 5 and 20): ","10");
  console.log("col " + col);
}
// notice the use of isNaN(row) which is checking the col variable

//declare variable as prompt first
var row = prompt("Rows (Int between 5 and 20): ","10");
/* ** continue to display prompt if user enters a number below 5 or a number above 20 or a character which is not a number ** */
while (row < 5 || row < 20 || isNaN(row)) {
  row = prompt("Rows (Int between 5 and 20): ","10");
  console.log("row " + row);
}
// notice the use of isNaN(row) which is checking the row variable

//First check if row is greated than col
if (row > col) {
  size = 400/col;console.log("More Rows " + row + "rows and " + col + "cols");//if true run this code
}
//if row is not greater than col then check if col is greater than row
else if (col > row) {
  size = 400/row;console.log("More Cols " + col + "cols" + row + "rows and ");//if true then run this code
}
//else row and col must be equal
else {
  size = 400/col;console.log("same amount");//so run this code run this code
}
//end if statement and move on with code
console.log("size " + size);

你肯定是在正确的轨道上。建议使用isNaN（）方法。

Javascript逻辑运算符混淆

2 个答案: