In C++ specifies constructors and conversion operators that don't allow implicit conversions or copy-initialization. In C# declares a user-defined type conversion operator that must be invoked with a cast. For MS SQL Server for-xml-EXPLICIT mode use the [for-xml-explicit] tag
Questions tagged [explicit]
405 questions
14
votes
7 answers
Casting "number 0" to char before appending it
Why would I need to explicitly cast number 0 to char before appending it to string using string::operator+?
using namespace std;
int main()
{
string s = "";
s += 65; // no compile error
s += (char)0; // requires explicit cast
//s…
B Faley
- 17,120
- 43
- 133
- 223
14
votes
3 answers
Why const char* implicitly converted to bool rather than std::string?
#include
#include
struct mystruct{
mystruct(std::string s){
std::cout<<__FUNCTION__ <<" String "<
TruthSeeker
- 1,539
- 11
- 24
14
votes
1 answer
usage of explicit keyword for constructors
I was trying to understand the usage of explicit keyword in c++ and looked at this question on SO
What does the explicit keyword mean in C++?
However, examples listed there (actually both top two answers) are not very clear regarding the usage. For…
SandBag_1996
- 1,570
- 3
- 20
- 50
14
votes
13 answers
Why is "explicitness" considered a Good Thing?
I often hear people praise languages, frameworks, constructs, etc. for being "explicit". I'm trying to understand this logic. The purpose of a language, framework, etc. is to hide complexity. If it makes you specify all kinds of details…
dsimcha
- 67,514
- 53
- 213
- 334
13
votes
3 answers
Explicit Assignment vs Implicit Assignment
I'm reading a tutorial for C++ but it didn't actually give me a difference (besides syntax) between the two. Here is a quote from the tutorial.
You can also assign values to your variables upon declaration. When we
assign values to a variable…
Freesnöw
- 30,619
- 30
- 89
- 138
13
votes
2 answers
explicit specifier doesn't seem to work when converting an object to bool
I am learning C++ recently and I noticed an example on cppreference, part of which goes like this:
struct B
{
explicit B(int) { }
explicit operator bool() const { return true; }
};
int main()
{
B b2(2); // OK:…
Jinlong Chen
- 141
- 4
13
votes
1 answer
Initialization with empty curly braces
First attempt and everything works fine:
class Base {
public:
Base() {std::cout << "default ctor!\n"; }
};
...
Base b{};
Base b_one = {};
Another way of implementation(add explicit):
class Base {
public:
explicit Base() {std::cout <<…
Gusev Slava
- 2,136
- 3
- 21
- 26
13
votes
5 answers
What is the difference between "Explicitly" and "Implicitly" in programming language?
I would like to have a clear and precise understanding of the difference between the two.
Also is the this keyword used to implicitly reference or explicitly ? This is also why I want clarification between the two?
I assume to use the this keyword…
Equivocal
- 912
- 2
- 14
- 27
13
votes
1 answer
Explicit copy constructor and std::sort
When sorting a container of objects having an explicit copy ctor I get compiler errors (from g++ 4.8.2 and clang++ 3.4, both in -std=c++11 mode) that I don't understand. I've created a simple example to demonstrate the problem
class A {
public:
…
Gerald Senarclens de Grancy
- 7,154
- 7
- 41
- 55
13
votes
1 answer
Why is `explicit` not compatible with `virtual`?
struct A
{
// error C2216: 'explicit' cannot be used with 'virtual'
virtual explicit operator bool() const
{
return true;
}
};
struct B : A
{
// error C2216: 'explicit' cannot be used with 'override'
explicit…
xmllmx
- 39,765
- 26
- 162
- 323
12
votes
2 answers
Why conversion function is not used for an object when it is assigned to?
I learned that we could provide conversion operators for our classes in C++. So I expected that for the following program, c=1; would've used the conversion operator int(). But to my surprise; that doesn't happen and we get a compiler error saying…
Sam
- 166
- 8
12
votes
1 answer
`auto x = type{...}` initialization syntax and `explicit` conversion operator - clang vs gcc
Given this code (on wandbox):
struct X
{
explicit operator int() { return 0; }
};
int main()
{
auto y = int{X{}};
}
And the following compiler options:
-std=c++1z -Wall -Wextra -Wpedantic
g++ (tested versions: 7, 6.1, 5.3) refuses to…
Vittorio Romeo
- 90,666
- 33
- 258
- 416
12
votes
2 answers
F#: explicit type parameters in operator binding
I'm trying to define operator with the explicit type parameters and constraints:
let inline (===)<'a, 'b
when 'a : not struct
and 'b : not struct> a b = obj.ReferenceEquals (a,b)
It works well in F# 2.0, but produces the:
warning FS1189:…
controlflow
- 6,667
- 1
- 31
- 55
12
votes
5 answers
Why does the compiler choose bool over string for implicit typecast of L""?
Having recently introduced an overload of a method the application started to fail.
Finally tracking it down, the new method is being called where I did not expect it to be.
We had
setValue( const std::wstring& name, const std::wstring& value…
Greg Domjan
- 13,943
- 6
- 43
- 59
12
votes
10 answers
Foo f = Foo(); // no matching function for call to 'Foo::Foo(Foo)' ... huh?
class Foo
{
public:
explicit Foo() {}
explicit Foo(Foo&) {}
};
Foo d = Foo();
error: no matching function for call to 'Foo::Foo(Foo)'
I tried changing Foo(Foo&) to Foo(Foo) as the error suggests, which AFAIK is not a valid constructor,…
Kyle
- 4,487
- 3
- 29
- 45