import type { TypeGuardFn } from './isType';
/**
 * Checks if a value is a valid number (excludes NaN).
 *
 * @param value - The value to check
 * @param config - Optional configuration for error handling
 * @returns True if the value is a valid number (not NaN), false otherwise
 *
 * @example
 * ```typescript
 * import { isNumber } from 'guardz';
 *
 * console.log(isNumber(123)); // true
 * console.log(isNumber(0)); // true
 * console.log(isNumber(-42.5)); // true
 * console.log(isNumber(Infinity)); // true
 * console.log(isNumber(NaN)); // false
 * console.log(isNumber("123")); // false
 * console.log(isNumber(null)); // false
 *
 * // With type narrowing
 * const data: unknown = getUserInput();
 * if (isNumber(data)) {
 *   // data is now typed as number
 *   console.log(data.toFixed(2));
 * }
 * ```
 */
export declare const isNumber: TypeGuardFn<number>;