limit.Exp(big.NewInt(10), big.NewInt(99), nil)

	// Loop while a is smaller than 1e100.
	for a.Cmp(&limit) < 0 {
		// Compute the next Fibonacci number, storing it in a.
		a.Add(a, b)
		// Swap a and b so that b is the next number in the sequence.
		a, b = b, a
	}
	fmt.Println(a) // 100-digit Fibonacci number

	// Test a for primality.
	// (ProbablyPrimes' argument sets the number of Miller-Rabin

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// Compute Fibonacci numbers with two goroutines
// that pass integers back and forth.  No actual
// concurrency, just threads and synchronization
// and foreign code on multiple pthreads.

package main

import (
	big "."
	"runtime"
)

// Usage:
// fibo <n>     compute fibonacci(n), n must be >= 0
// fibo -bench  benchmark fibonacci computation (takes about 1 min)
//
// Additional flags:
// -half        add values using two half-digit additions
// -opt         optimize memory allocation through reuse
// -short       only print the first 10 digits of very large fibonacci numbers

// Command fibo is a stand-alone test and benchmark to

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build test_run

// Compute Fibonacci numbers with two goroutines
// that pass integers back and forth.  No actual
// concurrency, just threads and synchronization
// and foreign code on multiple pthreads.

package main

import (
	"runtime"
	"strconv"

	"cgostdio/stdio"

	title = testname + " (written byte-by-byte)"
	b.clear()
	for i := 0; i < len(src); i++ {
		write(t, title, &w, src[i:i+1])
	}
	verify(t, title, &w, &b, src, expected)

	// write using Fibonacci slice sizes
	title = testname + " (written in fibonacci slices)"
	b.clear()
	for i, d := 0, 0; i < len(src); {
		write(t, title, &w, src[i:i+d])
		i, d = i+d, d+1
		if i+d > len(src) {
			d = len(src) - i
		}
	}

for u = range 256 {
}

// invalid: 1e3 is a floating-point constant
for range 1e3 {
}

// fibo generates the Fibonacci sequence
fibo := func(yield func(x int) bool) {
	f0, f1 := 0, 1
	for yield(f0) {
		f0, f1 = f1, f0+f1
	}
}

// print the Fibonacci numbers below 1000:
for x := range fibo {
	if x >= 1000 {
		break
	}
	fmt.Printf("%d ", x)
}