尝试添加2个数组时额外的0位

Question

我正在研究需要计算2个大整数的总和而不使用java中的biginteger类的程序。我卡在我的for循环计算总和。我得到一个额外的0，所以30 + 30 = 600.

我很确定这是因为我错误地循环访问数组。我需要去相反的方式（从右侧开始，就像你添加数字时一样），但我似乎无法修复它，没有得到数组索引错误。

这里是我的代码：

main: 

import java.util.Scanner; 

public class testLargeInteger 
{ 



public static void main(String[] args) 
    { 
    Scanner input = new Scanner(System.in); 
     String string1; 
     String string2; 
     int exp =0; 


     System.out.print("Enter the first integer: "); 
     //Store up the input string “string1” entered by the user from the keyboard. 
     string1 = input.next(); 

     LargeInteger firstInt = new LargeInteger(string1); 

     System.out.print("Enter the second integer: "); 
     string2 = input.next(); 
     //Store up the input string “string2” entered by the user from the keyboard. 
     LargeInteger secondInt = new LargeInteger(string2); 

     System.out.print("Enter the exponential integer: "); 
     //Store up the input integer “exp” entered by the user from the keyboard. 
     exp = input.nextInt(); 


     LargeInteger sum = firstInt.add(secondInt); 

     System.out.printf ("First integer: %s \n", firstInt.display()); 
     System.out.println("Second integer: " + secondInt.display()); 
     System.out.println(" Exponent: " + exp); 

     System.out.printf (" Sum = %s \n", sum.display()); 

    } 
} 

大整数：

public class LargeInteger { 


    private int[] intArray; 


    //convert the strings to array 
    public LargeInteger(String s) { 
     intArray = new int[s.length()]; 
     for (int i = 0; i < s.length(); i++) { 
      intArray[i] = Character.digit(s.charAt(i), 10); // in base 10 
     } 
    } 

    public LargeInteger(int[] array) { 
     intArray = array; 
    } 

    //display the strings 
    public String display() {   
      String result=""; 

      for (int i = 0; i < intArray.length; i++) {  
      result += intArray[i]; 
      } 
      return result.toString(); 
     } 

    //get first array 
    public int[] getIntArray() { 
      return intArray; 
     } 

    //ADD method to add 2 arrays together 
    public LargeInteger add(LargeInteger secondInt){ 

     int[] otherValues = secondInt.getIntArray(); 

     int maxIterations = Math.min(intArray.length, otherValues.length); 
     int currentResult; //to store result 
     int[] resultArray = new int[Math.max(intArray.length, otherValues.length) +1 ]; 

     int needToAdd = 0; //to store result should be added next step 

     for(int i = 0; i < maxIterations; i++) { 
      currentResult = intArray[i] + otherValues[i]; 
      resultArray[i] = currentResult % 10 + needToAdd; //if more than 9 its correct answer 
      needToAdd = currentResult/10; //this is what you need to add on next step 
     } 

     resultArray[Math.max(intArray.length, otherValues.length) ] = needToAdd; 

     return new LargeInteger(resultArray); 

    } 

} 

我试图改变的for循环总和是这样的：

for(int i = maxIterations; i >= 0; i--) 

Answer 1

那个for循环只是你的一个问题。

1]您没有正确添加进位。

2]堆栈比阵列更合适。

有一个堆栈（您的方法中的地方代码）： 注意：您正在使用number.add（num2）调用该函数;

public class LargeInt{ 
    private String number; 
    public LargeInt(String num){ 
     this.number = num; 
    } 

    public String add(String num2){ 
    Stack<Integer> adder = toIntegerStack(this.number);//UPDATE 
    Stack<Integer> addend = toIntegerStack(num2);//UPDATE 
    Stack<Integer> result = new Stack<Integer>(); 

    int carry =0; 
    int tmp = 0; 

    while(!.adder.isEmpty && !addend.isEmpty()){ 
    tmp = adder.pop()+addend.pop()+carry; 
    if(tmp > 10){ 
    carry = tmp/10; 
    tmp%=10; 
    }else{ 
    carry=0; 
    } 
    result.push(tmp); 
    }//while 

    while(!adder.isEmpty){ 
    tmp = adder.pop()+carry; 
    if(tmp > 10){ 
    carry = tmp/10; 
    tmp%=10; 
    }else{ 
    carry=0; 
    } 
    result.push(tmp); 
    }//while 

    while(!addend.isEmpty){ 
    tmp = addend.pop()+carry; 
    if(tmp > 10){ 
    carry = tmp/10; 
    tmp%=10; 
    }else{ 
    carry=0; 
    } 
    result.push(tmp); 
}//while 

//beyond this point the result is your answer 
//here convert your stack to string before returning 
} 
} 

UPDATE来回答评论： 我也编辑上面调用这个函数来填充堆栈。

private Stack<Integer> toIntegerStack(String n){ 
    Stack<Integer> stack = new Stack<Integer>(); 
    for(char c: n.toCharArray()) 
     stack.push(c-48);//ASCII 
    return stack; 
}//toStack(String) 

---

如果你坚持使用数组，你必须按照你的阵列相同的模式。

int indexA=0; 
int indexB=0; 
int[] result = new int[1+A.length>B.length?A.length:B.length]; 
int indexResult=result.length-1; 

while(indexA < A.length && indexB <B.length){//inside is same idea 
    tmp = A[indexA++] + B[indexB++] + carry; 
    //... do here as for stacks for tmp and carry 
    result[indexResult--]; 
} 

while(indexA < A.length){ 
    //do as in stack version 
} 

    while(indexB < B.length){ 
    //do as in stack version 
} 

Answer 2

你添加代码假设最低有效数字位于array[0]，但您的阅读代码将最多那里有数字。阅读后应该颠倒阵列。