Comparison and Boolean Tests

/**
 * Compare this number with another BN
 * @param {BN} num - Number to compare with
 * @returns {number} -1 if this < num, 0 if equal, 1 if this > num
 */
cmp(num: BN): number;

/**
 * Compare this number with a JavaScript number
 * @param {number} num - JavaScript number to compare with
 * @returns {number} -1 if this < num, 0 if equal, 1 if this > num
 */
cmpn(num: number): number;

/**
 * Unsigned comparison (ignoring signs)
 * @param {BN} num - Number to compare with
 * @returns {number} -1 if |this| < |num|, 0 if equal, 1 if |this| > |num|
 */
ucmp(num: BN): number;

const BN = require('bn.js');

const a = new BN('100');
const b = new BN('50');
const c = new BN('-25');

// Basic comparison
console.log(a.cmp(b));   // 1 (100 > 50)
console.log(b.cmp(a));   // -1 (50 < 100)
console.log(a.cmp(a));   // 0 (100 == 100)

// Compare with JavaScript number
console.log(a.cmpn(75)); // 1 (100 > 75)
console.log(b.cmpn(50)); // 0 (50 == 50)

// Unsigned comparison
console.log(b.ucmp(c));  // 1 (|50| > |-25|)

/**
 * Test equality with another BN
 * @param {BN} num - Number to compare with
 * @returns {boolean} True if numbers are equal
 */
eq(num: BN): boolean;

/**
 * Test equality with a JavaScript number
 * @param {number} num - JavaScript number to compare with
 * @returns {boolean} True if numbers are equal
 */
eqn(num: number): boolean;

/**
 * Test if this number is greater than another BN
 * @param {BN} num - Number to compare with
 * @returns {boolean} True if this > num
 */
gt(num: BN): boolean;

/**
 * Test if this number is greater than a JavaScript number
 * @param {number} num - JavaScript number to compare with
 * @returns {boolean} True if this > num
 */
gtn(num: number): boolean;

/**
 * Test if this number is greater than or equal to another BN
 * @param {BN} num - Number to compare with
 * @returns {boolean} True if this >= num
 */
gte(num: BN): boolean;

/**
 * Test if this number is greater than or equal to a JavaScript number
 * @param {number} num - JavaScript number to compare with
 * @returns {boolean} True if this >= num
 */
gten(num: number): boolean;

/**
 * Test if this number is less than another BN
 * @param {BN} num - Number to compare with
 * @returns {boolean} True if this < num
 */
lt(num: BN): boolean;

/**
 * Test if this number is less than a JavaScript number
 * @param {number} num - JavaScript number to compare with
 * @returns {boolean} True if this < num
 */
ltn(num: number): boolean;

/**
 * Test if this number is less than or equal to another BN
 * @param {BN} num - Number to compare with
 * @returns {boolean} True if this <= num
 */
lte(num: BN): boolean;

/**
 * Test if this number is less than or equal to a JavaScript number
 * @param {number} num - JavaScript number to compare with
 * @returns {boolean} True if this <= num
 */
lten(num: number): boolean;

const BN = require('bn.js');

const a = new BN('100');
const b = new BN('50');
const c = new BN('100');

// Equality tests
console.log(a.eq(c));    // true
console.log(a.eq(b));    // false
console.log(a.eqn(100)); // true

// Greater than tests
console.log(a.gt(b));    // true (100 > 50)
console.log(b.gt(a));    // false (50 < 100)
console.log(a.gte(c));   // true (100 >= 100)
console.log(a.gtn(75));  // true (100 > 75)

// Less than tests
console.log(b.lt(a));    // true (50 < 100)
console.log(a.lt(b));    // false (100 > 50)
console.log(a.lte(c));   // true (100 <= 100)
console.log(b.ltn(75));  // true (50 < 75)

/**
 * Test if the number is zero
 * @returns {boolean} True if the number equals zero
 */
isZero(): boolean;

/**
 * Test if the number is negative
 * @returns {boolean} True if the number is less than zero
 */
isNeg(): boolean;

/**
 * Test if the number is even
 * @returns {boolean} True if the number is divisible by 2
 */
isEven(): boolean;

/**
 * Test if the number is odd
 * @returns {boolean} True if the number is not divisible by 2
 */
isOdd(): boolean;

const BN = require('bn.js');

const zero = new BN('0');
const positive = new BN('42');
const negative = new BN('-17');
const even = new BN('100');
const odd = new BN('101');

// Zero test
console.log(zero.isZero());     // true
console.log(positive.isZero()); // false

// Sign test
console.log(negative.isNeg());  // true
console.log(positive.isNeg());  // false
console.log(zero.isNeg());      // false

// Even/odd tests
console.log(even.isEven());     // true
console.log(odd.isEven());      // false
console.log(even.isOdd());      // false
console.log(odd.isOdd());       // true

/**
 * Utility function to get the maximum of two BN numbers
 * @param {BN} left - First number
 * @param {BN} right - Second number  
 * @returns {BN} The larger of the two numbers
 */
BN.max(left: BN, right: BN): BN;

/**
 * Utility function to get the minimum of two BN numbers
 * @param {BN} left - First number
 * @param {BN} right - Second number
 * @returns {BN} The smaller of the two numbers
 */
BN.min(left: BN, right: BN): BN;

const BN = require('bn.js');

const a = new BN('100');
const b = new BN('200');

const maximum = BN.max(a, b);
const minimum = BN.min(a, b);

console.log(maximum.toString()); // "200"
console.log(minimum.toString()); // "100"

// Useful for bounds checking
const value = new BN('150');
const lowerBound = new BN('100');
const upperBound = new BN('200');

const isInRange = value.gte(lowerBound) && value.lte(upperBound);
console.log(isInRange); // true

const BN = require('bn.js');

function isInRange(value, min, max) {
  return value.gte(min) && value.lte(max);
}

const value = new BN('150');
const min = new BN('100');
const max = new BN('200');

console.log(isInRange(value, min, max)); // true

const BN = require('bn.js');

function findMax(bnArray) {
  if (bnArray.length === 0) return null;
  
  return bnArray.reduce((max, current) => 
    current.gt(max) ? current : max
  );
}

const numbers = [
  new BN('100'),
  new BN('250'), 
  new BN('175')
];

const maximum = findMax(numbers);
console.log(maximum.toString()); // "250"

const BN = require('bn.js');

const numbers = [
  new BN('300'),
  new BN('100'),
  new BN('200')
];

// Sort ascending
numbers.sort((a, b) => a.cmp(b));
console.log(numbers.map(n => n.toString())); // ["100", "200", "300"]

// Sort descending  
numbers.sort((a, b) => b.cmp(a));
console.log(numbers.map(n => n.toString())); // ["300", "200", "100"]