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langref: reword Hello World section (#18458)

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closes #14347
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Scott Schwarz 2024-01-08 00:32:26 -06:00 • committed by GitHub
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doc/langref.html.in
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@ -432,18 +432,17 @@ pub fn main() !void {
</p>
<p>
Next, a {#link|public function|Functions#}, {#syntax#}pub fn{#endsyntax#}, named {#syntax#}main{#endsyntax#}
is declared. The {#syntax#}main{#endsyntax#} function is necessary because it tells the Zig compiler where the start of
the program exists. Programs designed to be executed will need a {#syntax#}pub fn main{#endsyntax#} function.
is declared. The {#syntax#}main{#endsyntax#} function is necessary because it tells the Zig compiler where the program starts. Programs
designed to be executed will need a {#syntax#}pub fn main{#endsyntax#} function.
</p>
<aside role="note" aria-label="Note about main function">
<p>
For more advanced use cases, Zig offers other features to inform the compiler where the start of
the program exists. Also, libraries do not need a {#syntax#}pub fn main{#endsyntax#} function because
library code is called by other programs or libraries.
For more advanced use cases, Zig offers other features to inform the compiler where the program starts. Also, libraries do not need a
{#syntax#}pub fn main{#endsyntax#} function because library code is called by other programs or libraries.
</p>
</aside>
<p>
A function is a block of any number of statements and expressions that, as a whole, perform a task.
A function is a block of any number of statements and expressions, that as a whole, perform a task.
Functions may or may not return data after they are done performing their task. If a function
cannot perform its task, it might return an error. Zig makes all of this explicit.
</p>
@ -469,32 +468,30 @@ pub fn main() !void {
</aside>
<p>
In Zig, a function's block of statements and expressions are surrounded by an open curly-brace <code>{</code> and
close curly-brace <code>}</code>. Inside of the {#syntax#}main{#endsyntax#} function are expressions that perform
the task of outputting <samp>Hello, world!</samp> to standard output.
close curly-brace <code>}</code>. In <code class="file">hello.zig</code>, the {#syntax#}main{#endsyntax#} function
contains two statements.
</p>
<p>
First, a constant identifier, {#syntax#}stdout{#endsyntax#}, is initialized to represent standard output's
writer. Then, the program tries to print the <samp>Hello, world!</samp>
message to standard output.
In the first statement, a constant identifier, {#syntax#}stdout{#endsyntax#}, is initialized to represent standard output's
writer. In the second statement, the program tries to print the <samp>Hello, world!</samp> message to standard output.
</p>
<p>
Functions sometimes need information to perform their task. In Zig, information is passed
to functions between an open parenthesis {#syntax#}({#endsyntax#} and a close parenthesis {#syntax#}){#endsyntax#} placed after
the function's name. This information is also known as arguments. When there are
multiple arguments passed to a function, they are separated by commas {#syntax#},{#endsyntax#}.
Functions sometimes need inputs to perform their task. Inputs are passed, in between parentheses, to functions. These
inputs are also known as arguments. When multiple arguments are passed to a function, they are separated by commas.
</p>
<p>
The two arguments passed to the {#syntax#}stdout.print(){#endsyntax#} function, {#syntax#}"Hello, {s}!\n"{#endsyntax#}
and {#syntax#}.{"world"}{#endsyntax#}, are evaluated at {#link|compile-time|comptime#}. The code sample is
purposely written to show how to perform {#link|string|String Literals and Unicode Code Point Literals#}
substitution in the {#syntax#}print{#endsyntax#} function. The curly-braces inside of the first argument
are substituted with the compile-time known value inside of the second argument
(known as a {#link|tuple|Tuples#}). The <code>\n</code>
inside of the double-quotes of the first argument is the {#link|escape sequence|Escape Sequences#} for the
newline character. The {#link|try#} expression evaluates the result of {#syntax#}stdout.print{#endsyntax#}.
If the result is an error, then the {#syntax#}try{#endsyntax#} expression will return from
{#syntax#}main{#endsyntax#} with the error. Otherwise, the program will continue. In this case, there are no
more statements or expressions left to execute in the {#syntax#}main{#endsyntax#} function, so the program exits.
Two arguments are passed to the {#syntax#}stdout.print(){#endsyntax#} function: {#syntax#}"Hello, {s}!\n"{#endsyntax#}
and {#syntax#}.{"world"}{#endsyntax#}. The first argument is called a format string, which is a string containing one or
more placeholders. {#syntax#}"Hello, {s}!\n"{#endsyntax#} contains the placeholder {#syntax#}{s}{#endsyntax#}, which is
replaced with {#syntax#}"world"{#endsyntax#} from the second argument. The file <code class="file">string_literals.zig</code> in
{#link|String Literals and Unicode Code Point Literals|String Literals and Unicode Code Point Literals#} contains examples of format
strings that can be used with the {#syntax#}stdout.print(){#endsyntax#} function. The <code>\n</code> inside of
{#syntax#}"Hello, {s}!\n"{#endsyntax#} is the {#link|escape sequence|Escape Sequences#} for the newline character.
</p>
<p>
The {#link|try#} expression evaluates the result of {#syntax#}stdout.print{#endsyntax#}. If the result is an error, then the
{#syntax#}try{#endsyntax#} expression will return from {#syntax#}main{#endsyntax#} with the error. Otherwise, the program will continue.
In this case, there are no more statements or expressions left to execute in the {#syntax#}main{#endsyntax#} function, so the program exits.
</p>
<p>
In Zig, the standard output writer's {#syntax#}print{#endsyntax#} function is allowed to fail because