Read 4

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.

Create a 4-length char array buffer to keep read data.

Read data until get n size or buf is empty (size == 0), put the data which in tmp into buf.

public int read(char[] buf, int n) {

        int idx = 0;
        char [] tmp = new char[4];

        while(idx < n){

            int size = read4(tmp), i = 0;

            if(size == 0) break;

            while(idx < n && i < size){
                buf[idx ++] = tmp[i ++];
            }

        }

        return idx;
    }