Programming Forums > Script Programming > Python

G.I.Josh · Aug 5th, 2004, 11:32 AM

Hello. I know what both statements and expressions are, but it seems like from the processor's point of view there isn't much difference. The book I'm reading sais that statements are instructions that can be executed. Would not 1+1, an expression, be executed in the alu? Would that not make it a statement?

Infinite Recursion · Aug 5th, 2004, 1:10 PM

Variable declarations and initializations, etc are statements, as are the basic language structures like conditionals and loops.

Expressions are statements that produce a result that can be used as part of another statement. Method calls, object allocations, and, of course, mathematical expressions are examples of expressions.

Hopefully, that clears it up for you.

G.I.Josh · Aug 5th, 2004, 1:18 PM

Sure does. Thankya.

Infinite Recursion · Aug 5th, 2004, 1:21 PM

You're welcome

Ooble · Aug 5th, 2004, 1:46 PM

I take it the above complicated stuff simply means that statements return?

Infinite Recursion · Aug 5th, 2004, 3:38 PM

Complicated?

In short, expressions return values.

Kylixen · Aug 5th, 2004, 4:18 PM

Yea, I had something. It's gone now.

Ooble · Aug 5th, 2004, 5:55 PM

Quote:

Originally posted by Infinite Recursion@Aug 5 2004, 08:38 PM
Complicated?

In short, expressions return values.

That's what I meant... <_<

kurifu · Aug 7th, 2004, 12:53 AM

Actually executing 1+1 in the ALU would be a waste of time, as would the code that follows:

(Toggle Plain Text)

result = 1 + 2;

The reason being that we are working with constant values. Infact the compiler is going to look at this and optimize it so that result is just (re)initialized with the value of 3. Why would we want to computer otherwise constant values?

Even if you were to turn the optimizer off on this one I still believe that the code would be optimized as mentioned above since the compiler treats these explicitly as statements as opposed to expressions.

I would also like to point out that the operator

(Toggle Plain Text)

int operator+( int lhv, int rhv ){ return lhv + rhv; }

Would still treate the above code as a statement, despite the fact that the operator used to computer the value is returning a value (perhaps I am not understanding the question?)

Aug 5th, 2004, 11:32 AM	#1
G.I.Josh Programmer Join Date: Aug 2004 Location: Eastern U.S Posts: 51 Rep Power: 4	Hello. I know what both statements and expressions are, but it seems like from the processor's point of view there isn't much difference. The book I'm reading sais that statements are instructions that can be executed. Would not 1+1, an expression, be executed in the alu? Would that not make it a statement? __________________ http://exponentialab.blogspot.com/ - w00t, I've started a blog!

Aug 5th, 2004, 1:10 PM	#2
Infinite Recursion Programming Guru Join Date: Jul 2004 Location: United States Posts: 3,466 Rep Power: 8	Variable declarations and initializations, etc are statements, as are the basic language structures like conditionals and loops. Expressions are statements that produce a result that can be used as part of another statement. Method calls, object allocations, and, of course, mathematical expressions are examples of expressions. Hopefully, that clears it up for you. __________________ http://jasonpowers.net "There are a thousand hacking at the branches of evil to one who is striking at the root."

Aug 5th, 2004, 1:18 PM	#3
G.I.Josh Programmer Join Date: Aug 2004 Location: Eastern U.S Posts: 51 Rep Power: 4	Sure does. Thankya. __________________ http://exponentialab.blogspot.com/ - w00t, I've started a blog!

Aug 5th, 2004, 1:21 PM	#4
Infinite Recursion Programming Guru Join Date: Jul 2004 Location: United States Posts: 3,466 Rep Power: 8	You're welcome __________________ http://jasonpowers.net "There are a thousand hacking at the branches of evil to one who is striking at the root."

Aug 5th, 2004, 1:46 PM	#5
Ooble I eat cake for breakfast. Join Date: Jul 2004 Location: In my box. Posts: 4,434 Rep Power: 9	I take it the above complicated stuff simply means that statements return? __________________ Me :: You :: Them

Aug 5th, 2004, 3:38 PM	#6
Infinite Recursion Programming Guru Join Date: Jul 2004 Location: United States Posts: 3,466 Rep Power: 8	Complicated? In short, expressions return values. __________________ http://jasonpowers.net "There are a thousand hacking at the branches of evil to one who is striking at the root."

Aug 5th, 2004, 4:18 PM	#7
Kylixen Programmer Join Date: Jun 2004 Location: SC Posts: 60 Rep Power: 5	Yea, I had something. It's gone now. __________________ ALLOW IMAGES IN SIGNATURES NOW

Aug 7th, 2004, 12:53 AM	#9
kurifu Expert Programmer Join Date: Jul 2004 Location: Halifax, Nova Scotia (Canada) Posts: 784 Rep Power: 5	Actually executing 1+1 in the ALU would be a waste of time, as would the code that follows: (Toggle Plain Text) result = 1 + 2; result = 1 + 2; The reason being that we are working with constant values. Infact the compiler is going to look at this and optimize it so that result is just (re)initialized with the value of 3. Why would we want to computer otherwise constant values? Even if you were to turn the optimizer off on this one I still believe that the code would be optimized as mentioned above since the compiler treats these explicitly as statements as opposed to expressions. I would also like to point out that the operator (Toggle Plain Text) int operator+( int lhv, int rhv ){ return lhv + rhv; } int operator+( int lhv, int rhv ){ return lhv + rhv; } Would still treate the above code as a statement, despite the fact that the operator used to computer the value is returning a value (perhaps I am not understanding the question?) __________________ Clifford Matthew Roche <geek@cliffordroche.com> Web Hosting: http://www.crd-hosting.com Consulting: http://www.crdev-consulting.com

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Programming Forums > Script Programming > Python

Statements Vs. Expressions