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The problem is that `vector` cannot default-initialize any parameters. Nor
can any other container (where that would make sense, of course).

Therefore, I propose this syntax:

std::vector<T> copyInit(42, T{});
std::vector<T> valueInit(42);
std::vector<T> defaultInit(42, std::default_init);

`std::default_init` is a value of type `std::default_init_t`. It should be
fine.

And, combining with my idea about more uniform initialization in the
standard library:

std::vector<T> copyInit{42, T{}};
std::vector<T> valueInit{42, std::value_init};
std::vector<T> defaultInit{42, std::default_init};

This can be very useful for creating vectors (and other sequence
containers, like strings and such) of trivial types, since they will
default initialize their members. This is especially useful for loading
data into blocks of memory managed by `vector<char>` and so forth.

--




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<br><br>The problem is that `vector` cannot=20
default-initialize any parameters. Nor can any other container (where=20
that would make sense, of course).<br><br>Therefore, I propose this syntax:=
<br><br><div class=3D"prettyprint" style=3D"background-color: rgb(250, 250,=
 250); border-color: rgb(187, 187, 187); border-style: solid; border-width:=
 1px; word-wrap: break-word;"><code class=3D"prettyprint"><div class=3D"sub=
prettyprint"><span style=3D"color: #000;" class=3D"styled-by-prettify">std<=
/span><span style=3D"color: #660;" class=3D"styled-by-prettify">::</span><s=
pan style=3D"color: #000;" class=3D"styled-by-prettify">vector</span><span =
style=3D"color: #660;" class=3D"styled-by-prettify">&lt;</span><span style=
=3D"color: #000;" class=3D"styled-by-prettify">T</span><span style=3D"color=
: #660;" class=3D"styled-by-prettify">&gt;</span><span style=3D"color: #000=
;" class=3D"styled-by-prettify"> copyInit</span><span style=3D"color: #660;=
" class=3D"styled-by-prettify">(</span><span style=3D"color: #066;" class=
=3D"styled-by-prettify">42</span><span style=3D"color: #660;" class=3D"styl=
ed-by-prettify">,</span><span style=3D"color: #000;" class=3D"styled-by-pre=
ttify"> T</span><span style=3D"color: #660;" class=3D"styled-by-prettify">{=
});</span><span style=3D"color: #000;" class=3D"styled-by-prettify"><br>std=
</span><span style=3D"color: #660;" class=3D"styled-by-prettify">::</span><=
span style=3D"color: #000;" class=3D"styled-by-prettify">vector</span><span=
 style=3D"color: #660;" class=3D"styled-by-prettify">&lt;</span><span style=
=3D"color: #000;" class=3D"styled-by-prettify">T</span><span style=3D"color=
: #660;" class=3D"styled-by-prettify">&gt;</span><span style=3D"color: #000=
;" class=3D"styled-by-prettify"> valueInit</span><span style=3D"color: #660=
;" class=3D"styled-by-prettify">(</span><span style=3D"color: #066;" class=
=3D"styled-by-prettify">42</span><span style=3D"color: #660;" class=3D"styl=
ed-by-prettify">);</span><span style=3D"color: #000;" class=3D"styled-by-pr=
ettify"><br>std</span><span style=3D"color: #660;" class=3D"styled-by-prett=
ify">::</span><span style=3D"color: #000;" class=3D"styled-by-prettify">vec=
tor</span><span style=3D"color: #660;" class=3D"styled-by-prettify">&lt;</s=
pan><span style=3D"color: #000;" class=3D"styled-by-prettify">T</span><span=
 style=3D"color: #660;" class=3D"styled-by-prettify">&gt;</span><span style=
=3D"color: #000;" class=3D"styled-by-prettify"> defaultInit</span><span sty=
le=3D"color: #660;" class=3D"styled-by-prettify">(</span><span style=3D"col=
or: #066;" class=3D"styled-by-prettify">42</span><span style=3D"color: #660=
;" class=3D"styled-by-prettify">,</span><span style=3D"color: #000;" class=
=3D"styled-by-prettify"> std</span><span style=3D"color: #660;" class=3D"st=
yled-by-prettify">::</span><span style=3D"color: #000;" class=3D"styled-by-=
prettify">default_init</span><span style=3D"color: #660;" class=3D"styled-b=
y-prettify">);</span><span style=3D"color: #000;" class=3D"styled-by-pretti=
fy"><br></span></div></code></div><br>`std::default_init` is a value of typ=
e `std::default_init_t`. It should be fine.<br><br>And, combining with my i=
dea about more uniform initialization in the standard library:<br><br><div =
class=3D"prettyprint" style=3D"background-color: rgb(250, 250, 250); border=
-color: rgb(187, 187, 187); border-style: solid; border-width: 1px; word-wr=
ap: break-word;"><code class=3D"prettyprint"><div class=3D"subprettyprint">=
<span style=3D"color: #000;" class=3D"styled-by-prettify">std</span><span s=
tyle=3D"color: #660;" class=3D"styled-by-prettify">::</span><span style=3D"=
color: #000;" class=3D"styled-by-prettify">vector</span><span style=3D"colo=
r: #660;" class=3D"styled-by-prettify">&lt;</span><span style=3D"color: #00=
0;" class=3D"styled-by-prettify">T</span><span style=3D"color: #660;" class=
=3D"styled-by-prettify">&gt;</span><span style=3D"color: #000;" class=3D"st=
yled-by-prettify"> copyInit</span><span style=3D"color: #660;" class=3D"sty=
led-by-prettify">{</span><span style=3D"color: #066;" class=3D"styled-by-pr=
ettify">42</span><span style=3D"color: #660;" class=3D"styled-by-prettify">=
,</span><span style=3D"color: #000;" class=3D"styled-by-prettify"> T</span>=
<span style=3D"color: #660;" class=3D"styled-by-prettify">{}};</span><span =
style=3D"color: #000;" class=3D"styled-by-prettify"><br>std</span><span sty=
le=3D"color: #660;" class=3D"styled-by-prettify">::</span><span style=3D"co=
lor: #000;" class=3D"styled-by-prettify">vector</span><span style=3D"color:=
 #660;" class=3D"styled-by-prettify">&lt;</span><span style=3D"color: #000;=
" class=3D"styled-by-prettify">T</span><span style=3D"color: #660;" class=
=3D"styled-by-prettify">&gt;</span><span style=3D"color: #000;" class=3D"st=
yled-by-prettify"> valueInit</span><span style=3D"color: #660;" class=3D"st=
yled-by-prettify">{</span><span style=3D"color: #066;" class=3D"styled-by-p=
rettify">42</span><span style=3D"color: #660;" class=3D"styled-by-prettify"=
>,</span><span style=3D"color: #000;" class=3D"styled-by-prettify"> std</sp=
an><span style=3D"color: #660;" class=3D"styled-by-prettify">::</span><span=
 style=3D"color: #000;" class=3D"styled-by-prettify">value_init</span><span=
 style=3D"color: #660;" class=3D"styled-by-prettify">};</span><span style=
=3D"color: #000;" class=3D"styled-by-prettify"><br>std</span><span style=3D=
"color: #660;" class=3D"styled-by-prettify">::</span><span style=3D"color: =
#000;" class=3D"styled-by-prettify">vector</span><span style=3D"color: #660=
;" class=3D"styled-by-prettify">&lt;</span><span style=3D"color: #000;" cla=
ss=3D"styled-by-prettify">T</span><span style=3D"color: #660;" class=3D"sty=
led-by-prettify">&gt;</span><span style=3D"color: #000;" class=3D"styled-by=
-prettify"> defaultInit</span><span style=3D"color: #660;" class=3D"styled-=
by-prettify">{</span><span style=3D"color: #066;" class=3D"styled-by-pretti=
fy">42</span><span style=3D"color: #660;" class=3D"styled-by-prettify">,</s=
pan><span style=3D"color: #000;" class=3D"styled-by-prettify"> std</span><s=
pan style=3D"color: #660;" class=3D"styled-by-prettify">::</span><span styl=
e=3D"color: #000;" class=3D"styled-by-prettify">default_init</span><span st=
yle=3D"color: #660;" class=3D"styled-by-prettify">};</span></div></code></d=
iv><br>This
 can be very useful for creating vectors (and other sequence containers,
 like strings and such) of trivial types, since they will default=20
initialize their members. This is especially useful for loading data=20
into blocks of memory managed by `vector&lt;char&gt;` and so forth.

<p></p>

-- <br />
&nbsp;<br />
&nbsp;<br />
&nbsp;<br />

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