# Hello, Zig

### Hello, Zig

The first program in Zig is small.

```zig
const std = @import("std");

pub fn main() void {
    std.debug.print("hello, zig\n", .{});
}
```

Save this in a file named `main.zig`.

Run it:

```sh
zig run main.zig
```

The output is:

```text
hello, zig
```

A Zig program is made of declarations. The first line declares a name:

```zig
const std = @import("std");
```

`const` means the name cannot be changed after it is set. Here the name is `std`. The value comes from `@import("std")`, which imports Zig's standard library.

The next declaration is a function:

```zig
pub fn main() void {
    ...
}
```

`fn` begins a function declaration. The function is named `main`. This is where the program starts.

`pub` makes the function visible outside the file. For an executable program, `main` must be visible to the compiler.

The word after the parameter list is the return type:

```zig
void
```

`void` means the function returns no value.

The body of the function is inside braces:

```zig
{
    std.debug.print("hello, zig\n", .{});
}
```

This calls `std.debug.print`.

The first argument is a string:

```zig
"hello, zig\n"
```

The `\n` means newline.

The second argument is:

```zig
.{}
```

`std.debug.print` uses this second argument for values that should be inserted into the string. There are no inserted values in this example, so the argument is an empty tuple.

A slightly larger version prints a number:

```zig
const std = @import("std");

pub fn main() void {
    const year = 2026;
    std.debug.print("Zig in {d}\n", .{year});
}
```

The output is:

```text
Zig in 2026
```

The `{d}` in the string says: print a decimal integer. The value comes from the tuple:

```zig
.{year}
```

Zig does not hide much here. A name is declared. A function is called. The format string says what to print. The values to print are passed explicitly.

This is the usual shape of a small Zig program:

```zig
const std = @import("std");

pub fn main() void {
    // work goes here
}
```

Exercise 1-1. Run the first program.

Exercise 1-2. Change the message.

Exercise 1-3. Print two lines.

Exercise 1-4. Declare a constant named `name` and print it with `{s}`.