Initial commit

src/main.zig

@@ -0,0 +1,73 @@
+const std = @import("std");
+
+pub fn main(init: std.process.Init) !void {
+    const allocator = init.gpa;
+    const io = init.io;
+
+    var stdout_buffer: [1024]u8 = undefined;
+    var stdout = std.Io.File.stdout().writer(io, &stdout_buffer);
+    var output = &stdout.interface;
+
+    const nmax = getInput(io, "Please enter a maximum prime seek number") catch |err| {
+        try output.print("Error while acquiring number input: {}\n", .{err});
+        try output.flush();
+        return;
+    };
+
+    var primes = getPrimes(allocator, nmax) catch |err| {
+        try output.print("Failed to get primes: {}\n", .{err});
+        try output.flush();
+        return;
+    };
+    defer primes.deinit(allocator);
+
+    if (primes.items.len == 0) {
+        try output.writeAll("No prime numbers were found\n");
+        try output.flush();
+        return;
+    }
+
+    const last = primes.items[primes.items.len - 1];
+    try output.print("Displaying {d} prime numbers from 2 to {d}:\n", .{primes.items.len, last});
+    for (primes.items) |prime| {
+        try output.print("{d} ", .{prime});
+    }
+    try output.flush();
+}
+
+fn getInput(io: std.Io, message: []const u8) !usize {
+    var stdin_buffer: [100]u8 = undefined;
+    var stdout_buffer: [1024]u8 = undefined;
+
+    var stdin = std.Io.File.stdin().reader(io, &stdin_buffer);
+    var stdout = std.Io.File.stdout().writer(io, &stdout_buffer);
+
+    var line_buffer: [100]u8 = undefined;
+    var w: std.Io.Writer = .fixed(&line_buffer);
+
+    try stdout.interface.print("{s}: ", .{message});
+    try stdout.flush();
+
+    const line_length = try stdin.interface.streamDelimiterLimit(&w, '\n', .unlimited);
+    const input: []const u8 = line_buffer[0..line_length];
+
+    return std.fmt.parseInt(usize, input, 10);
+}
+
+fn getPrimes(allocator: std.mem.Allocator, n_max: usize) !std.ArrayList(usize) {
+    var primes: std.ArrayList(usize) = .empty;
+
+    for (2..n_max+1) |i| {
+        if (isPrime(i)) try primes.append(allocator, i);
+    }
+
+    return primes;
+}
+
+fn isPrime(n: usize) bool {
+    for (2..n) |i| {
+        if (n % i == 0) return false;
+    }
+
+    return true;
+}