字符串在内存中是不可变的，放在只读内存段，因此你可以使用str[0]来访问，但是不能使用str[0]='a'来修改。
Is there any clever way to mix two bit sequences in such way that bits from first sequence will be on odd places, and bits from second sequence will be on even places.
加载中,请稍侯......