+function (a) {

    a.fn = a.prototype;

    var fn = {

        /**

         * 进制转换

         * @param to

         * @returns {string}

         */

        toBits: function (to) {

            var bits = [];

            var t = this;

            var i = 0;

            for (i; i < t.length; i++) {

                var code = t.charCodeAt(i);

                bits.push(code.toString(to));

            }

            bits.reverse();

            return bits.join("");

        },

        /**

         * 去除右变指定字符串.默认空白

         * @returns {XML|string|void|*}

         */

        rtrim: function () {

            var replace = arguments[0] || "\\s";

            var r = new RegExp("(^" + replace + "{1,})");

            return this.replace(r, '');

        },

        /**

         * 去除左边指定字符串.默认空白

         * @returns {XML|string|void|*}

         */

        ltrim: function () {

            var replace = arguments[0] || "\\s";

            var r = new RegExp("(" + replace + "{1,}$)");

            return this.replace(r, '');

        },

        /**

         * 去除两边指定字符串.默认空白

         * @returns {XML|string|void|*}

         */

        trim: function () {

            var str = this, a = arguments;

            str = str.ltrim.apply(str.rtrim.apply(str, a), a);

            return str;

        },

        str_repeat: function (i, m) {

            for (var o = []; m > 0; o[--m] = i);

            return o.join('');

        },

        /**

         * c的sprintf实现

         * @returns {string}

         */

        sprintf: function () {

            var i = 0, a, f = this.toString(), o = [], m, p, c, x, s = '';

            while (f) {

                if (m = /^[^\x25]+/.exec(f)) {

                    o.push(m[0]);

                }

                else if (m = /^\x25{2}/.exec(f)) {

                    o.push('%');

                }

                else if (m = /^\x25(?:(\d+)\$)?(\+)?(0|'[^$])?(-)?(\d+)?(?:\.(\d+))?([b-fosuxX])/.exec(f)) {

                    if (((a = arguments[m[1] || i++]) == null) || (a == undefined)) {

                        throw('Too few arguments.');

                    }

                    if (/[^s]/.test(m[7]) && (typeof(a) != 'number')) {

                        throw('Expecting number but found ' + typeof(a));

                    }

                    switch (m[7]) {

                        case 'b':a = a.toString(2);break;

                        case 'c':a = this.fromCharCode(a); break;

                        case 'd':a = parseInt(a);break;

                        case 'e':a = m[6] ? a.toExponential(m[6]) : a.toExponential(); break;

                        case 'f':a = m[6] ? parseFloat(a).toFixed(m[6]) : parseFloat(a);break;

                        case 'o':a = a.toString(8);break;

                        case 's':a = ((a = String(a)) && m[6] ? a.substring(0, m[6]) : a);break;

                        case 'u':a = Math.abs(a);break;

                        case 'x':a = a.toString(16); break;

                        case 'X':a = a.toString(16).toUpperCase();break;

                    }

                    a = (/[def]/.test(m[7]) && m[2] && a >= 0 ? '+' + a : a);

                    c = m[3] ? m[3] == '0' ? '0' : m[3].charAt(1) : ' ';

                    x = m[5] - String(a).length - s.length;

                    p = m[5] ? this.str_repeat(c, x) : '';

                    o.push(s + (m[4] ? a + p : p + a));

                }

                else {

                    throw('Huh ?!');

                }

                f = f.substring(m[0].length);

            }

            return o.join('');

        }

    };

    for (var i in fn) {

        a.fn[i] = fn[i];

    }

    window.String = a;

}(String);