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langref: reword Hello World section (#18458)

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