Here is the code,
Why does the output result include "one"? Thanks.Code:
int main()
{
int i=4;
switch(i)
{
default:printf("zero\n");
case 1: printf("one\n");
break;
case 2:printf("two\n");
break;
case 3: printf("three\n");
break;
}
return 0;
}
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Here is the code,
Why does the output result include "one"? Thanks.Code:
int main()
{
int i=4;
switch(i)
{
default:printf("zero\n");
case 1: printf("one\n");
break;
case 2:printf("two\n");
break;
case 3: printf("three\n");
break;
}
return 0;
}
What did you expect to print? Where is the break statement for the default case?Quote:
Originally Posted by LarryChen
Regards,
Paul McKenzie
Actually, I expected the output to be just "zero". Since i is 4, so it doesn't satisfy case 1.Quote:
Originally Posted by Paul McKenzie
Again, where is the break statement for the default case? Do you know why break makes a difference?Quote:
Originally Posted by LarryChen
Regards,
Paul McKenzie
And if you set i to equal 1, and your case 1 didn't include a break statement, what do you think the output would be?Quote:
Originally Posted by LarryChen
I thought case statement is like if statement. So in my example, when i is 4 and it meets case 1, then case 1 is not going to be entered. Why am I wrong? Thanks.Quote:
Originally Posted by Paul McKenzie
That's been answered twice by Paul and once by me already. Basically a switch statement starts at the first case that meets the expression and keeps going till it hits a break.Quote:
Originally Posted by LarryChen
Larry, don't you see your reasoning is faulty?Quote:
Originally Posted by LarryChen
OK, so what does break do? What purpose does it serve if, by your reasoning, once a case condition is met, the switch is exited as soon as the next case condition is met? If that's your conclusion, then why not just remove the break statements from case 1, case 2, and case 3? It's just unnecessary typing, according to your conclusion.
The answer is as GCDEF mentioned -- break does mean something in a case statement, and that is to ensure that the condition doesn't "fall through" to the next case condition.
Regards,
Paul McKenzie
This "fall through" into the next case behaviour is sometimes a very handy feature of how the switch in C++ works. (as opposed to other programming languages where this isn't possible)