Basic Pointer Usage in Zig

This Zig program demonstrates the fundamentals of working with pointers in a safe and explicit manner.

const std = @import("std");

pub fn main(_: std.process.Init.Minimal) void {
    var x: i32 = 42;
    const ptr: *i32 = &x;
    std.debug.print("Memory address of x: {}\n", .{ptr});

    // Print the original value of x via the pointer
    std.debug.print("Value of x via pointer: {}\n", .{ptr.*});

    ptr.* = 100;
    std.debug.print("Modified value of x via pointer: {}\n", .{x});
}

The program starts by importing the standard library with const std = @import("std"); and defines a minimal main() function that takes std.process.Init.Minimal as a parameter and returns void, indicating no error handling is needed for this simple example.

Inside main(), an integer variable x of type i32 is declared and initialized to 42. A pointer ptr of type *i32 is then created using the address-of operator &x, which points to the memory location of x. The program prints the memory address of x using std.debug.print("Memory address of x: {}\n", .{ptr});, showcasing how Zig can directly output pointer values for debugging purposes.

Next, it dereferences the pointer with ptr.* to access and print the original value of x (42). The code then modifies the value at the pointed location by assigning ptr.* = 100;, which directly updates the original variable x through the pointer. Finally, it prints the modified value of x to confirm the change (now 100).

Save it as ptr.zig and execute it:

$ zig run ptr.zig
Memory address of x: i32@16f17a9b4
Value of x via pointer: 42
Modified value of x via pointer: 100

Happy coding in Zig!