【有用的算法】

1、阿拉伯数字转中文读法代码

Tips：仅整数，万万亿往上有bug；提供Java、Objective-C版本代码

测试数据：

110000：一十一万
100000200：一亿零二百
1000000323：一十亿零三百二十三
9999100323340034：九千九百九十九万亿一千零三亿二千三百三十四万零三十四

Java版

public String numberConvert(double n) {
    if (n < 0) return "异常";
    double number = n;
    String[] numberChars = {"零","一","二","三","四","五","六","七","八","九"};
    String[] units = {"", "十", "百", "千", "万","十", "百", "千", "亿", "十",
            "百", "千", "万亿", "十", "百", "千", "万万亿", "十", "百", "千", "?"};
    StringBuilder result = new StringBuilder();
    int index = 0, isZero = 0; // index：数值单位下标递增，isZero：是否插入零，多个零只需读一个
    while (number >= 1) {
        if (index >= units.length) break;
        int pop = (int) (number % 10);
        number /= 10; // 从低位依次取出组成number的数字
        String unit = units[index ++];
        String readNum = numberChars[pop];
        if (pop > 0) result.insert(0, unit);
        else if (index % 4 == 1) result.insert(0, unit); // 避免零字后刚好跟单位
        if (pop != 0) {
            result.insert(0, readNum);
            isZero = 0;
        } else if (isZero == 0) { // readNum = 零且可插入零时，再避免零后刚好跟单位
            if (index % 4 != 1) result.insert(0, readNum);
            isZero = 1;
        }
    }
    if (n == 0) result.append(numberChars[0]);
    if (n / 10000 % 10000 < 1) {    // 解决亿级数字万级全零多了个万字问题
        int s = result.lastIndexOf("万");
        if (s > 0 && s + 1 < result.length())
            if (result.charAt(s + 1) != '零')
                result.replace(s, s + 1, "零");
            else result.delete(s, s + 1);
    }
    return result.toString();
}

Objective-C版

- (NSString *)numberConvert:(long)n {
    if (n < 0) return @"异常";
    long number = n;
    NSArray *numberChars = @[@"零", @"一", @"二", @"三", @"四", @"五", @"六", @"七", @"八", @"九"];
    NSArray *units = @[@"", @"十", @"百", @"千", @"万", @"十", @"百", @"千", @"亿", @"十", @"百",
                       @"千", @"万亿", @"十", @"百", @"千", @"万万亿", @"十", @"百", @"千", @"?"];
    NSMutableString *result = [[NSMutableString alloc] initWithCapacity:0];
    int index = 0, isZero = 0; // index：数值单位下标递增，isZero：是否插入零，多个零只需读一个
    while (number > 0) {
        if (index >= units.count) break;
        int pop = (int)(number % 10);
        number /= 10; // 从低位依次取出组成number的数字
        NSString *unit = units[index ++];
        NSString *readNum = numberChars[pop];
        if (pop > 0) [result insertString:unit atIndex:0];
        else if (index % 4 == 1) [result insertString:unit atIndex:0]; // 避免零字后刚好跟单位
        if (pop != 0) {
            [result insertString:readNum atIndex:0];
            isZero = 0;
        } else if (isZero == 0) { // readNum = 零且可插入零时，再避免零后刚好跟单位
            if (index % 4 != 1) [result insertString:readNum atIndex:0];
            isZero = 1;
        }
    }
    if (n == 0) [result appendString:numberChars[0]];
    if(n / 10000 % 10000 < 1) {    // 解决亿级数字万级全零多了个万字问题
        NSRange range = [result rangeOfString:units[4] options:NSBackwardsSearch];
        // PS：此处还应判断越界
        if ([[result substringWithRange:NSMakeRange(range.location + 1, 1)] isEqual:@"零"])
            [result deleteCharactersInRange:range];
        else [result replaceCharactersInRange:range withString:numberChars[0]];
    }
    return result;
}