[英]Sum of two long values returns negative value
我已經編寫了代碼來完成后綴評估,除非我試圖處理下面的情況,我繼續得到一個負值,我知道這是不正確的。 為什么我得到這個負數,我如何得到正確的 output 18000000000000000000? 我已經在下面發布了我的代碼,任何幫助將不勝感激。
public static Number postfixEvaluate(String e){
Long number1;
Long number2;
Number result = new Long(0);
Stack<Number> stack = new Stack();
String[] tokens = e.split(" ");
for(int j = 0; j < tokens.length; j++){
String token = tokens[j];
//System.out.println(tokens[j]);
if (!"+".equals(token) && !"*".equals(token) && !"-".equals(token) && !"/".equals(token) && !"".equals(token)) {
stack.push(Long.parseLong(token));
} else if ("".equals(token)) {
System.out.println(token);
} else {
String Operator = tokens[j];
number2 = (Long) stack.pop();
System.out.println(number2);
number1 = (Long) stack.pop();
System.out.println(number1);
if (Operator.equals("/")){
result = number1 / number2;
System.out.println(result);
}
else if(Operator.equals("*")){
result = number1 * number2;
System.out.println(result);
}
else if(Operator.equals("+")){
result = Long.sum(number1, number2);
System.out.println("Addition of: " + number1 + "+ " + number2 + "= " + result);
}
else if(Operator.equals("-")){
result = number1 - number2;
System.out.println(result);
}
else System.out.println("Illeagal symbol");
stack.push(result);
}
}
stack.pop();
//s.pop();
System.out.println("Postfix Evauation = " + result);
return result;
}
我的輸入和 output:
Input: 9000000000000000123 9000000000000000987 +
Expected Output: 18000000000000000000
Current Output: -446744073709550506
你得到了負值,因為你超過了一個long
可以持有的最大值。 當您超過最大值時,它會從最小值重新開始,直到超過最大值的數量。 當您嘗試將小於最小值的數字分配給long
變量時,也是如此。 要理解這一點,可以看下面程序的output:
public class Main {
public static void main(String[] args) {
System.out.println("Long.MAX_VALUE: "+Long.MAX_VALUE);
System.out.println("Long.MIN_VALUE: "+Long.MIN_VALUE);
long x = Long.MAX_VALUE + 1;
long y = Long.MIN_VALUE - 1;
System.out.println("Long.MAX_VALUE + 1: "+x);//will be assigned the value of Long.MIN_VALUE
System.out.println("Long.MIN_VALUE - 1: "+y);//will be assigned the value of Long.MAX_VALUE
x = Long.MAX_VALUE + 2;
y = Long.MIN_VALUE - 2;
System.out.println("Long.MAX_VALUE + 2: "+x);//will be assigned the value of Long.MIN_VALUE + 1
System.out.println("Long.MIN_VALUE - 2: "+y);//will be assigned the value of Long.MAX_VALUE - 1
}
}
Output:
Long.MAX_VALUE: 9223372036854775807
Long.MIN_VALUE: -9223372036854775808
Long.MAX_VALUE + 1: -9223372036854775808
Long.MIN_VALUE - 1: 9223372036854775807
Long.MAX_VALUE + 2: -9223372036854775807
Long.MIN_VALUE - 2: 9223372036854775806
根據您的要求,您需要BigInteger
例如
BigInteger bi = new BigInteger("18000000000000000000");
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