 What other useful casts can be used in C++
By : user1017946
Date : March 29 2020, 07:55 AM
I wish did fix the issue. My favorite and most loved cast is implicit_cast. It only succeeds if the types can be implicitly converted. Useful for conversion from some type into void* or from some derived class into a base (if you want to select a specific instance of an overloaded function or constructor) or to safely add const-qualifications and any other scenario where you really just need implicit conversions to happen and even static_cast is too powerful. code :
template<typename T> struct identity { typedef T type; };
template<typename Dst> Dst implicit_cast(typename identity<Dst>::type t)
{ return t; }
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 Javascript: Validate field (on a form) so that it can only have Letters, 1 hyphen allowed, and 1 apostrophe allowed
By : Van Winkle
Date : March 29 2020, 07:55 AM
this will help this is my first time really coding in javascript and I've come to a dead end on my part. I need to make a function (no RegExp allowed unfortunately) that allows my pizza form to validate a user's input. To make sure it ONLY has letters (no numbers, no spaces, no special characters aside from hyphen and apostrophe). code :
function validatefield01(errMessages){
var entry1_info = document.f1.sDate.value
//if character count is less than 4 or greater than 15.
if ((entry1_info.length < 4) || (entry1_info.length > 15)) {
// error message to be displayed
errMessages += " <li>Minimum characters for Client Surname is 4 maximum 15\n";
return false;
}
var word = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcedfghijklmnopqrstuvwxyz-'";
// Check input string validation.
for ( var i = 0; i < entry1_info.length; i++) {
if (word.indexOf(entry1_info.charAt(i), 0) == -1) {
// error message to be displayed.
errMessages += "must use characters only, Apostrophe ( ' ) or hyphen (-) is acceptable.</li>\n";
return false;
}
}
document.f1.sDate.value = entry1_info.substring(0).toUpperCase();
return true;
}
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C++ like vs C like casts?
By : Trần Nhật Tiền
Date : March 29 2020, 07:55 AM
hop of those help? C-style casts are unsafe.
C++-style casts behave in another way. static_cast will give you a compilation error if it can't make the cast. dynamic_cast on fail will cast to NULL if you are casting pointers, and throw an exception otherwise.
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 Subqueries are not allowed in this context. Only scalar expressions are allowed in CREATE TABLE with AS syntax
By : Rami
Date : March 29 2020, 07:55 AM
seems to work fine Computed columns are used to ensure columns persisted property within the table itself. In your case, you need to have another update after you created table, populate the column by the query similar to below query, also, you need to create Foreign Key in the Total Cost column based on what you try to achieve. code :
UPDATE A
SET A.[Total Cost] = A.[Length of time in hours] * B.[Cost per hour] --add ISNULL to treat NULL if needed
FROM [Rooms Rented] as A
INNER JOIN [Rooms] as B
ON B.Room_ID = A.Room_ID
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If I use C-Style casts in my C++ project, is it worth refactoring to C++ casts?
By : codecloud
Date : March 29 2020, 07:55 AM
hop of those help? The main advantage of the C++-style casts is, as you've mentioned, the type safety. Each cast in C++ handles one specific sort of conversion (or a family of related conversions) and so the compiler can go and check that you're not accidentally doing more conversions that you intended, or a sequence of conversions that fundamentally isn't safe.
One thing to think about is that while it's great that you feel comfortable using C-style casts, and while it's great that you haven't made any mistakes with them, other people working on the code base might not be as facile with these casts as you are. Using the casting operators makes the code more self-documenting. If you have a C-style cast somewhere, someone else reading the code might not be able to immediately infer what it is that you're doing. If they see something like
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