Meaning

[Esmo2000]

What would the following conditional (i+n) in a for loop evaluate to? for (i=0; i + n; i--) I saw it once, but I dont understand what was happening. Did I post well? Rate it! Did I post badly? Rate that too!

[David Crow]

0 if n starts at 0. Otherwise non-zero, thus the for loop would never terminate.

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"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

[Esmo2000]

I want to believe you, but I cannot. int k = 0; int i, n=100; for (i=0; i + n; i--) k++; When this is done, k will equal 100. Can you explain? Did I post well? Rate it! Did I post badly? Rate that too!

[cmk]

The for test is: i + n which is the same as: i + n != 0 n = 100 so we can rewrite as: i + 100 != 0 or (subtract 100 from both sides), i != -100 so as i starts at 0 and decrements by 1 on each iteration it will loop 100 times. ...cmk Save the whales - collect the whole set

[David Crow]

It helps to show all of the code up front. Since n starts out as 100, rather than 0 as I initially presumed, i + n will eventually evaluate to 0 which will terminate the loop.

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"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

[toxcct]

in C/C++, booleans can be reprensented the following way :

0 equals to false
any other values different from 0 equals to true

so, as (i + n) would equal to 100, it is true - until it become equals to 0... you follow me ? :-D

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TOXCCT >>> GEII power
[toxcct][VisualCalc]

[cpm2]

Surely if n was -1 it would not evaluate to 1, but to zero, so the for loop would not loop forever?

Helpful

[David Crow]

In the code snippet provided by Esmo2000, when does n ever equal -1?

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"Ideas are a dime a dozen. People who put them into action are priceless." - Unknown

[TheGreatAndPowerfulOz]

for n < 0 the loop will execute until i wraps around to abs(n) for n == 0 the loop will never execute (i+0) == 0 == false for n > 0 the loop will execute n times

[cpm2]

:-) I hadn't seen that response yet

Helpful