布爾變量來確定素數asp.net

Question

我需要使用一個布爾變量來確定是否插入一個文本框，一個數是質數，可以用C＃編寫

protected void isPrimeButton_Click(object sender, EventArgs e) 
{ 

    int TestNumber = int.Parse(primeNumberTextBox.Text); 
    bool isPrime = true; 

    for (int i = 0; i < TestNumber; i++) 
    { 
     while (TestNumber % i == 0) 
     { 
      bool isPrime = true; 
      yesNoPrimeTextBox.Text = "prime"; 
      break; 
     } 

     while (TestNumber % i == 0) 
     { 
      bool isPrime = false; 

      yesNoPrimeTextBox.Text = "not prime"; 
      break; 

     } 
    } 
} 

Answer 1

不是很有效率，但這個肩膀d工作：

protected void isPrimeButton_Click(object sender, EventArgs e) 
{ 

    int TestNumber = int.Parse(primeNumberTextBox.Text); 
    bool isPrime = true; 

    for (int i = 2; i < TestNumber; i++) 
    { 
     if (TestNumber % i == 0) 
     { 
      isPrime = false; 
      break; 
     } 
    } 
    if (isPrime) 
     yesNoPrimeTextBox.Text = "prime"; 
    else 
     yesNoPrimeTextBox.Text = "not prime"; 

} 

Answer 2

這應該這樣做。

保護無效isPrimeButton_Click（對象發件人，EventArgs的）{

int TestNumber = int.Parse(primeNumberTextBox.Text); 
bool isPrime = false; 

for (int i = 2; i < TestNumber-1; i++) 
{ 
    if (TestNumber % i == 0) 
    { 
     isPrime = true; 
     yesNoPrimeTextBox.Text = "prime"; 
     break; 
    }  
} 

}

Answer 3

提取IsPrime作爲方法，你就會有這樣的事情：

public static Boolean IsPrime(int value) { 
    if (value <= 1) 
    return false; 
    else if (value <= 3) // 2 and 3 are primes 
    return true; 
    else if (value % 2 == 0) // even numbers (2 excluded) are not primes 
    return false; 

    // Test odd numbers 3, 5, 7, ... as potential dividers 
    // up to square root of the value 
    int n = (int) (Math.Sqrt(value) + 1); 

    for (int i = 3; i <= n; i += 2) 
    if (value % i == 0) 
     return false; 

    return true; 
} 

... 

protected void isPrimeButton_Click(object sender, EventArgs e) { 
    int testNumber; 

    if (!int.TryParse(primeNumberTextBox.Text, out testNumber)) { 
    // primeNumberTextBox.Text is not a int (incorrect format) 
    //TODO: probably you have to put some text into yesNoPrimeTextBox.Text 
    return; 
    } 

    if (IsPrime(testNumber)) 
    yesNoPrimeTextBox.Text = "prime"; 
    else 
    yesNoPrimeTextBox.Text = "not prime"; 
} 

Answer 4

使用此方法來檢查： 也可以考慮改變返回類型，也許你希望它返回boolean變量，而不是字符串

 public static string CheckPrime(int number) 
    { 
     bool isPrime = true; 
     for (int i = 2; i < number; i++) 
     { 
      if (number % i == 0) 
      { 
       isPrime = false; 
       break; 
      } 
     } 
     if (isPrime) 
     { 

      return number.ToString() + " is a Prime number"; 
     } 
     else 
     { 
      return number.ToString() + " is not a Prime number"; 
     } 
    }