Read N Characters Given Read4算法详解

算法题目：The API: int read4(char *buf) reads 4 characters at a time from a file.
The return value is the actual number of characters read. For example, it returns 3 if there is only 3 characters left in the file.
By using the read4 API, implement the function int read(char *buf, int n) that reads n characters from the file.

Note:
The read function will only be called once for each test case.

大致意思：用一个只读取4个字符的API，实现一个读取n个字符的API

int read4(char[] buf);int read(char* buf, int n){    char* buffer=new char[4];    int readBytes=0;    bool eof=false;    while(!eof&&readBytes<n)    {        int lsize=read4(buffer);        if(lsize<4)eof=true;        if((readBytes+lsize)>n)        {            memcpy(buf+readBytes,buffer,n-readBytes);            readBytes=n;        }        else        {            memcpy(buf+readBytes,buffer,lsize);            readBytes+=lsize;        }    }    return readBytes;}