Java-循环

Question

I'm writing a for-loop for an assignment in school. The loop will write the min number, ex. 26 and will increase with 7 every turn in the loop until it reaches max, ex. 112. Between every number, the will also be written a comma - ",". But not after the last number.

Right now my code looks like this:

int min=26;
int max=112;

for(int i=min; i<=max; i+=7)
{
   if(i!=max)
   {
      System.out.print(i+", ");
   }
   else
   {
      System.out.print(i);
   }

}

Right now the last number will have a comma... Where's my problem?

Answer 1

Others have explained that i may not ever be equal to max . For a case like this, it's easier to wait until the next loop iteration to print the comma:

for(int i=min; i<=max; i+=7)
{
   if(i!=min)
   {
      System.out.print(", "+i);
   }
   else
   {
      System.out.print(i);
   }

}

(Often I'll set up a separate boolean named first to see if I'm going through the first iteration; it's set to true before the loop and false at the end of the loop.)

PS There are other ways to solve the problem, such as changing the i==max condition or computing the actual maximum. However, the above approach can be applied in lots of cases that don't have anything to do with stepping by a fixed amount, and where it might not be as easy to figure out ahead of time when the loop will stop.

Answer 2

It never enters else loop, because in your code max = 112 , but your for loop won't reach that value. (It reaches 110 after increments of 7). So it will only execute the `if' loop and print the strings with comma, and then exit.

Answer 3

Since 'i' will never be equal to 'max', the else clause is not executed.
If 'min' is always less than 'max', then you can also do:

int min=26;
int max=112;

System.out.print(min);
for(int i=min+7; i<=max; i+=7)
{
    System.out.print("," + i);
}

Answer 4

After 12 loops: 26+7*12 = 110. It will exit the loop and the second condition will never be met.

int min=26;
int max=112;

for(int i=min; i<=max; i+=7) {
    if(i <= max-7)
        System.out.print(i+", ");
    else
        System.out.print(i);
}

Answer 5

Chances are that in the last iteration of the loop, i is not equal to max , given that your increment step y 7 . Actually, your loop runs from 26 to 112 , that's 86 which is not multiple of 7 .

You should be fine if you calculate your max value based on min and step, something like.-

int step = 7;
int min = 26;
int max = min * step;

for(int i = min; i <= max; i += step)

Answer 6

Your max value is 112 and your min value is 26. You're incrementing 7 at each iteration. If you subtract 26 from 112, you will see that the result is not multiple of 7, which means your loop is not stopping when i is exactly 112. Rather, your loop ends before i reaches value 112. That's why you see a comma in the end of the printed string.