为了练习,我试图通过将两个非常长的整数放在数组中并在数组中添加相应的元素来添加它们。然而,当试图添加结转时,我遇到了问题(即,结转是1,例如,当你做199+199=398时,你会添加到十位)。
当我做167+189时,我得到了正确的答案,是356。然而,对于这个例子(199+199),我得到的是288,而不是398。我的问题是,如果结转在我进行167+189时效果良好,为什么我在进行199+199时得到错误的答案?
if (stringNumOneLength == stringNumTwoLength)
{ int answer;
int carryOver = 0;
int answerArray[] = new int[stringNumOneLength + 1];
for (int i = 1; i <= stringNumTwoLength; i = i + 1)
{
answer = Character.getNumericValue(stringNumOne.charAt(stringNumOneLength - i)) + Character.getNumericValue(stringNumTwo.charAt(stringNumTwoLength - i) + carryOver);
System.out.println(answer);
if (answer >= 10)
{
for (int j = 0; j <= 9; j = j + 1)
{
if (10 + j == answer)
{
carryOver = 1;
answer = j;
System.out.println("The carryover is " + carryOver + ".");
}
}
}
else
{
carryOver = 0;
}
answerArray[stringNumOneLength + 1 - i] = answer;
}
System.out.println(Arrays.toString(answerArray));
}
输出如下:
[1,9,9]
[1,9,9]
18
结转为1。
8
2
[0,2,8,8]
您将进位添加到字符而不是其值:
... + Character.getNumericValue(stringNumTwo.charAt(stringNumTwoLength - i) + carryOver);
您希望在+中移动右侧的父对象。
请注意,您的for循环是不必要的。这做了同样的事情:
if (answer >= 10)
{
answer -= 10;
carryOver = 1;
System.out.println("The carryover is 1.");
}
else ...
如果您对惯用的解决方案感兴趣:
public class Test {
public String add(String a, String b) {
StringBuilder r = new StringBuilder();
int carry = 0;
for (int ia = a.length() - 1, ib = b.length() - 1; ia >= 0 || ib >= 0; ia--, ib--) {
int aDigit = ia < 0 ? 0 : Character.getNumericValue(a.charAt(ia));
int bDigit = ib < 0 ? 0 : Character.getNumericValue(b.charAt(ib));
int sum = carry + aDigit + bDigit;
if (sum >= 10) {
sum -= 10;
carry = 1;
}
else {
carry = 0;
}
r.append(Character.forDigit(sum, 10));
}
if (carry > 0) {
r.append('1');
}
return r.reverse().toString();
}
public void run() {
System.out.println("789 + 89 = " + add("789", "89"));
System.out.println("12 + 128 = " + add("12", "128"));
System.out.println("999 + 999 = " + add("999", "999"));
}
public static void main(String[] args) {
new Test().run();
}
}
此行的括号:
answer = Character.getNumericValue(stringNumOne.charAt(stringNumOneLength - i)) + Character.getNumericValue(stringNumTwo.charAt(stringNumTwoLength - i) + carryOver);
是错误的。注意+ carryOver
是如何在Character.getNumericValue.的调用中的