Is there a right or wrong practice when using IF statements : if(foo) or if(foo == true)?

问题

Throughout my (short) career so far in programming (merely a student working on internship) I have noticed that when it comes to IF statements, there is two different ways of doing it.

If we take foo as a boolean value:

if(foo)
{
    //do stuff
}

This is my preferred way of doing things when dealing with IF statements, if I'm looking for false I use:

if(!foo)
{
    //do more stuff
}

However, when some people see this they raise an eyebrow, suggesting that I may be stuck in a bad habit. But I wanted to know, is there any difference between this way or the "typical" way?

if(foo == true)
{
    //do a bit more stuff
}

Am I falling into a common trap for new programmers? Or is there no difference (at least a noticeable one)

回答1:

I never write == true or == false. It goes against the point of an if-sentence, in my opinion.

an if is basicly: If a Boolean expression is true, do something. a Boolean is a boolean expression in and of itself, so why wrap it?

So in my opinion, the ones using == true are the ones with a bad habit. Becuase they display ignorance of how the language works.

think of these "allowed" ways to write if (Foo) and if (!Foo):

if (Foo == true) //If Foo is the same as true
if (Foo != true //If Foo is not the same as true
if (Foo != false) //if Foo is not the same as false
if (Foo == false) //If Foo is the same as false
if (Foo) //If Foo
if (!Foo) //If not Foo

using == and != with booleans actually introduce new ways to make mistakes both when programming and reading code.

Boolean and !Boolean is hard to misread.

回答2:

I guess doing it your way is recommended in most of the languages

if(foo)
{
    //do stuff
}

For instance Python PEP8 says

Don't compare boolean values to True or False using ==.

Yes:   if greeting:
No:    if greeting == True:
Worse: if greeting is True:

Another example from Code Conventions for the Java Programming Language 7

The if-else class of statements should have the following form:

if (condition) {
    statements;
}

Just the small tip: Speaking about condition checks, here's the good tip I've heard few weeks ago If you compare for instance in C like

if(variable == "value") ....

you can get to the problems that if you write by accident if (variable = "value") ... compiler will not throw an error, so some people use the convention of if ("value" == variable) ..., then if you write by accident = instead of ==, compiler will throw an error

回答3:

Most coding conventions tell you that boolean checks are tested as

if(someBoolean) {

if(!someBoolean) {

This simply improves readability. If you are unsure, check out some code conventions, here are the Java ones for you: http://www.oracle.com/technetwork/java/javase/documentation/codeconvtoc-136057.html

回答4:

Checking if(foo == true) means

check if foo is equal to true is equal to true

Which is just an overhead according to me.

来源：https://stackoverflow.com/questions/14976344/is-there-a-right-or-wrong-practice-when-using-if-statements-iffoo-or-iffoo

标签

validation

if-statement

logic