/**
 * Transforms the first letter of a string to upper case.
 * @param {String} str String to transform
 * @returns {String}
 */
export declare function firstToUpper(str: string): string;
/**
 * Returns a number formatted to show only 2 digits after the decimal point.
 * @param {number} num
 * @returns {Number}
 */
export declare function twoDigitFormat(num: number): number;
/**
 * Switch the index of one member of an array with another member.
 * @param {Array} arr
 * @param {number} i1
 * @param {number} i2
 * @returns {Array}
 */
export declare function switchMembers([...arr]: [], i1: number, i2: number): [];
/**
 * Returns a new array which starts from index, adds the rest of the members to it's end.
 * @param {Array} array Array to rearrange.
 * @param {number} index to arrange from.
 * @returns {Array}
 */
export declare function rearrangeArray<T>([...array]: T[], index: number): T[];
/**
 * Map a string substring to a different string.
 * @param {string} str String to reduce.
 * @param {string} toMap Substring to reduce.
 * @param {string} mapTo String to reduce to.
 * @returns {string}
 */
export declare function mapString(str: string, toMap: string, mapTo: string): string;
/** Function that count occurrences of a substring in a string.
 * @param {String} str               The string
 * @param {String} subString            The sub string to search for
 * @returns {number}
 */
export declare function occurrencesInString(str: string, subString: string): number;
/**
 * Fills an array with it's own elements to fit a certain size.
 * @param arr The array to fit.
 * @param size The new size.
 * @returns {Array}
 */
export declare function fitArrayToSize<T>([...arr]: Array<T>, size: number): Array<T>;
/**
 * Returns the longest array from an array of arrays.
 * @param matrix Array of arrays
 * @returns {Array}
 */
export declare function longestArray<T>(matrix: Array<Array<T>>): Array<T>;
/**
 * Returns true if string represents a number, else false.
 * @param {String} str
 * @returns {boolean}
 */
export declare function isNumberAsString(str: string): boolean;