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Comparison Operators

General Info: Round Floating Point Numbers

When comparing floating point numbers, make sure you round to an acceptable level of rounding for the type of application you are using.

Languages Focus

A comparison operator compares two values either literals as in "Hello" and 3 or variables as in X and Counter. Most languages use the same operators for comparing both numbers and strings. Perl, for example, uses separate sets of comparison operators for numbers and strings.

Delphi:   =, <>

Common comparison operators:

= equal
<> not equal
< less than
> greater than
<= less than or equal
>= greater than or equal

Syntax Example:
//Does Delphi evaluate the math correctly? Yes!
//Refer to math.pas MaxSingle for more info.
if (0.1 + 0.1 + 0.1 = 0.3) then
ShowMessage('correct')
else
ShowMessage('not correct')




Cross Reference Examples:

Access VBA:   =, <>

Save as VB Classic. Common comparison operators:

= equal
<> not equal
< less than
> greater than
<= less than or equal
>= greater than or equal

Syntax Example:
//Does Access evaluate the math correctly? No!
If 0.1 + 0.1 + 0.1 = 0.3 Then
MsgBox "correct"
Else
MsgBox "not correct"
End If
ASP Classic:   =, <>

Save as VB Classic. Common comparison operators:

= equal
<> not equal
< less than
> greater than
<= less than or equal
>= greater than or equal
Syntax Example:
//Does ASP evaluate the math correctly? No!
If .1 + .1 + .1 = .3 Then
Response.Write "correct"
Else
Response.Write "not correct"
End If
C#:   ==, !=

Common comparison operators:

== equal
!= not equal
< less than
> greater than
<= less than or equal
>= greater than or equal

Syntax Example:
//Does C# evaluate the math correctly? No!
if (.1 + .1 + .1 == .3)
MessageBox.Show("correct");
else
MessageBox.Show("not correct");
C++:   ==, !=

Common comparison operators:

== equal
!= not equal
< less than
> greater than
<= less than or equal
>= greater than or equal

Syntax Example:
//C++Builder example (ShowMessage is a VCL method).
//Does C++Builder evaluate the math correctly? No!
If (.1 + .1 + .1 == .3)
ShowMessage("correct");
else
ShowMessage("not correct");
C++/CLI:   ==, !=

Same as standard C++. Common comparison operators:

== equal
!= not equal
< less than
> greater than
<= less than or equal
>= greater than or equal
Syntax Example:
//Does C++/CLI evaluate the math correctly? No!
if (0.1 + 0.1 + 0.1 == 0.3)
MessageBox::Show("correct");
else
MessageBox::Show("not correct");
Corel Paradox:   =, <>

Common comparison operators:

= equal
<> not equal
< less than
> greater than
<= less than or equal
>= greater than or equal

Syntax Example:
'Does ObjectPAL evaluate the math correctly? No!
If .1 + .1 + .1 = .3 Then
msgInfo("", "correct")
Else
msgInfo("", "not correct")
endIf
Delphi Prism:   =, <>

Same as Delphi. Common comparison operators:

= equal
<> not equal
< less than
> greater than
<= less than or equal
>= greater than or equal
Syntax Example:
//Does Prism evaluate the math correctly? No!
//This is different than later versions of 
//Delphi that muse MaxSingle in math.pas.
If .1 + .1 + .1 = .3 Then
MessageBox.Show("correct")
Else
MessageBox.Show("not correct");
Java:   ==, !=

The Java comparison operators are:

== equal
!= not equal
< less than
> greater than
<= less than or equal
>= greater than or equal

More Info / Comment
JavaScript:   ==, !=

Common comparison operators:

== equal
!= not equal
< less than
> greater than
<= less than or equal
>= greater than or equal

Syntax Example:
//Does JavaScript evaluate the math correctly? No!
if (.1 + .1 + .1 == .3) {
document.write("correct");
}
else {
document.write("not correct");
}
Perl:   ==, !=

Common comparison operators:

== equal
!= not equal
< less than
> greater than
<= less than or equal
>= greater than or equal

Perl also offers additional string comparison operators:

eq string equals
ne string not equal
lt string less than
gt string greater than
le string less than or equal
ge string greater than or equal

Syntax Example:
#Does Perl evaluate the math correctly? No!
if ((.1 + .1 + .1) == .3) {
print("Correct<br>");
} else {
print("Not correct<br>");
}
PHP:   ==, != or <>

Common comparison operators:

== equal
!= or <> not equal
< less than
> greater than
<= less than or equal
>= greater than or equal

PHP 4 and above also offers === for indentical (equal plus same type) and !== for not identical (not equal or not same type).

Syntax Example:
//Does PHP evaluate the math correctly? No!
if (.1 + .1 + .1 == .3) {
echo "correct";
}
else {
echo "not correct";
}
VB Classic:   =, <>

Common comparison operators:

= equal
<> not equal
< less than
> greater than
<= less than or equal
>= greater than or equal
Syntax Example:
//Does VB evaluate the math correctly? No!
If 0.1 + 0.1 + 0.1 = 0.3 Then
MsgBox "correct"
Else
MsgBox "not correct"
End If
VB.Net:   =, <>

Save as VB Classic. Common comparison operators:

= equal
<> not equal
< less than
> greater than
<= less than or equal
>= greater than or equal

Syntax Example:  
//Does VB.Net evaluate the math correctly? No!
If 0.1 + 0.1 + 0.1 = 0.3 Then
MessageBox.Show("correct")
Else
MessageBox.Show("not correct")
End If




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