Should one use < or <= in a for loop [closed]

Answer 1

In C++, I prefer using !=, which is usable with all STL containers. Not all STL container iterators are less-than comparable.

Answer 2

I always use < array.length because it's easier to read than <= array.length-1.

also having < 7 and given that you know it's starting with a 0 index it should be intuitive that the number is the number of iterations.

Answer 3

This falls directly under the category of "Making Wrong Code Look Wrong".

In zero-based indexing languages, such as Java or C# people are accustomed to variations on the index < count condition. Thus, leveraging this defacto convention would make off-by-one errors more obvious.

Regarding performance: any good compiler worth its memory footprint should render such as a non-issue.

Answer 4

The '<' and '<=' operators are exactly the same performance cost.

The '<' operator is a standard and easier to read in a zero-based loop.

Using ++i instead of i++ improves performance in C++, but not in C# - I don't know about Java.

Answer 5

In Java 1.5 you can just do

for (int i: myArray) {
    ...
}

so for the array case you don't need to worry.

Answer 6

First, don't use 6 or 7.

Better to use:

int numberOfDays = 7;
for (int day = 0; day < numberOfDays ; day++){

}

In this case it's better than using

for (int day = 0; day <= numberOfDays  - 1; day++){

}

Even better (Java / C#):

for(int day = 0; day < dayArray.Length; i++){

}

And even better (C#)

foreach (int day in days){// day : days in Java

}

The reverse loop is indeed faster but since it's harder to read (if not by you by other programmers), it's better to avoid in. Especially in C#, Java...