英文:
Convert from int to hexadecimal string to check if it contains a word
问题
我们正在做以下的编程练习：[Death by Coffee][1]。
主要任务是将整数转换为十六进制并进行值的相加。我们编写了以下代码：
public class Dinglemouse {
public static int[] coffeeLimits /*☕*/ (final int year, final int month, final int day) {
System.out.println("year: "+year);
System.out.println("month: "+month);
System.out.println("day: "+day);
long healthNumber = Long.parseLong(String.valueOf(year)+String.valueOf(month)+String.valueOf(day));
System.out.println("healthNumber: "+healthNumber);
long cafe = Long.valueOf("CAFE",16);
long decaf = Long.valueOf("DECAF",16);
int cafeLimit = getLimit(cafe, healthNumber);
System.out.println("\ncafeLimit: "+cafeLimit);
int decafLimit = getLimit(decaf, healthNumber);
System.out.println("\ndecafLimit: "+decafLimit);
return new int []{cafeLimit, decafLimit};
}
public static int getLimit(long coffee, long healthNumber){
int limit=0;
while(limit<=5000 && !Long.toHexString(healthNumber).contains("dead")){
limit++;
healthNumber+=coffee;
System.out.println("new healthNumber: "+Long.toHexString(healthNumber));
}
return limit>5000 ? 0 : limit;
}
}
我们想知道为什么代码通过以下的测试，除了 exJohn：
import org.junit.Test;
import static org.junit.Assert.*;
import java.util.*;
public class Tests {
// Show returned limits
private static int[] show(final int y, final int m, final int d, final int[] result) {
System.out.println(String.format("%4d%02d%02d -> ",y,m,d)+Arrays.toString(result));
return result;
}
@Test
public void exJohn() {
final int y=1950, m=1, d=19;
assertArrayEquals(new int[]{2645,1162}, show(y,m,d,Dinglemouse.coffeeLimits(y,m,d)));
}
@Test
public void exSusan() {
final int y=1965, m=12, d=11;
assertArrayEquals(new int[]{111,0}, show(y,m,d,Dinglemouse.coffeeLimits(y,m,d)));
}
@Test
public void exElizabeth() {
final int y=1964, m=11, d=28;
assertArrayEquals(new int[]{0,11}, show(y,m,d,Dinglemouse.coffeeLimits(y,m,d)));
}
@Test
public void exPeter() {
final int y=1965, m=9, d=4;
assertArrayEquals(new int[]{0,0}, show(y,m,d,Dinglemouse.coffeeLimits(y,m,d)));
}
}
我们已经打印出在 `getLimit` 循环内部得到的内容，我们发现咖啡限制的最后一个 `healthNumber` 输出为：
...
new healthNumber: 2dc4cbb
new healthNumber: 2dd17b9
new healthNumber: 2dde2b7
new healthNumber: 2deadb5
cafeLimit: 889
而对于无咖啡因限制，我们有：
...
new healthNumber: 10ff8a241
new healthNumber: 110068ef0
new healthNumber: 110147b9f
new healthNumber: 11022684e
decafLimit: 0
因此，我们的代码结果是：
[889, 0]
而实际上应该是：
[2645, 1162]
我们认为可能是整数溢出导致的，因此我们将所有变量都更改为 long，但程序的行为仍然相同。
我们已阅读过：
- [https://stackoverflow.com/questions/9321553/java-convert-integer-to-hex-integer](https://stackoverflow.com/questions/9321553/java-convert-integer-to-hex-integer)
- [https://stackoverflow.com/questions/5258415/how-to-get-a-hex-value-from-a-decimal-integer-in-java](https://stackoverflow.com/questions/5258415/how-to-get-a-hex-value-from-a-decimal-integer-in-java)
- [https://stackoverflow.com/questions/11194513/convert-hex-string-to-int](https://stackoverflow.com/questions/11194513/convert-hex-string-to-int)
[1]: [https://www.codewars.com/kata/57db78d3b43dfab59c001abe](https://www.codewars.com/kata/57db78d3b43dfab59c001abe)
英文:
we are doing the following programming exercise: Death by Coffee.
The main task is to convert from integers to hexadecimals and add values. We have written the following code:
public class Dinglemouse {
public static int[] coffeeLimits /*☕*/ (final int year, final int month, final int day) {
System.out.println("year: "+year);
System.out.println("month: "+month);
System.out.println("day: "+day);
long healthNumber = Long.parseLong(String.valueOf(year)+String.valueOf(month)+String.valueOf(day));
System.out.println("healthNumber: "+healthNumber);
long cafe = Long.valueOf("CAFE",16);
long decaf = Long.valueOf("DECAF",16);
int cafeLimit = getLimit(cafe, healthNumber);
System.out.println("\ncafeLimit: "+cafeLimit);
int decafLimit = getLimit(decaf, healthNumber);
System.out.println("\ndecafLimit: "+decafLimit);
return new int []{cafeLimit, decafLimit};
}
public static int getLimit(long coffee, long healthNumber){
int limit=0;
while(limit<=5000 && !Long.toHexString(healthNumber).contains("dead")){
limit++;
healthNumber+=coffee;
System.out.println("new healthNumber: "+Long.toHexString(healthNumber));
}
return limit>5000 ? 0 : limit;
}
}
We wonder why the code passes the following tests, except exJohn:
import org.junit.Test;
import static org.junit.Assert.*;
import java.util.*;
public class Tests {
// Show returned limits
private static int[] show(final int y, final int m, final int d, final int[] result) {
System.out.println(String.format("%4d%02d%02d -> ",y,m,d)+Arrays.toString(result));
return result;
}
@Test
public void exJohn() {
final int y=1950, m=1, d=19;
assertArrayEquals(new int[]{2645,1162}, show(y,m,d,Dinglemouse.coffeeLimits(y,m,d)));
}
@Test
public void exSusan() {
final int y=1965, m=12, d=11;
assertArrayEquals(new int[]{111,0}, show(y,m,d,Dinglemouse.coffeeLimits(y,m,d)));
}
@Test
public void exElizabeth() {
final int y=1964, m=11, d=28;
assertArrayEquals(new int[]{0,11}, show(y,m,d,Dinglemouse.coffeeLimits(y,m,d)));
}
@Test
public void exPeter() {
final int y=1965, m=9, d=4;
assertArrayEquals(new int[]{0,0}, show(y,m,d,Dinglemouse.coffeeLimits(y,m,d)));
}
}
We have printed what we get inside getLimit's loop, and we see that the last healthNumber being output for cafe limit is:
...
new healthNumber: 2dc4cbb
new healthNumber: 2dd17b9
new healthNumber: 2dde2b7
new healthNumber: 2deadb5
cafeLimit: 889
And for the decaf limit we have:
...
new healthNumber: 10ff8a241
new healthNumber: 110068ef0
new healthNumber: 110147b9f
new healthNumber: 11022684e
decafLimit: 0
So then our code's result is:
[889, 0]
When it should be:
[2645, 1162]
We thought it could be caused by int overflow so we changed all variables to long, however the program behaves equal.
We have read:
答案1
得分: 0
以下是您要求的翻译内容：
您的代码行
long healthNumber = Long.parseLong(String.valueOf(year)+String.valueOf(month)+String.valueOf(day));
中的 "eats" 掉了日期和月份前面的零，您可以将其替换为类似以下方式：
long healthNumber = year*10000+month*100+day;
以使其按预期工作。
英文:
Your line of code
long healthNumber = Long.parseLong(String.valueOf(year)+String.valueOf(month)+String.valueOf(day));
"eats" leading zeroes in day and month, you can replace it with something like
long healthNumber = year*10000+month*100+day;
to make it work as expected.
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