fstream.read() 根本不读取任何内容

Question

我正在尝试读取 MP3 文件的第一行（我编辑了此 mp3 文件以在文件开头包含文本“我是 MP3”）。

这就是我想做的：

#include <iostream>
#include <string>
#include <fstream>
using namespace std;

int main()
{
    fstream mp3;
    mp3.open("05 Imagine.mp3", ios::binary | ios::in | ios::out);
    /*mp3.seekg(0, ios::end);
    int lof = mp3.tellg();
    cout << "Length of file: " << lof << endl;
    mp3.seekg(0, ios::beg);*/

    //char ch;
    //cout << mp3.get(ch) << endl;

    char* somebuf;
    while(mp3.read(somebuf, 10)) //Read the first 10 chars which are "I'm an MP3 file".
    {
        //cout << somebuf;
    }
    return 0;
}

出于某种原因，这正在崩溃。在某些时候它没有崩溃，但是当我执行 cout << 时它没有打印任何内容。一些缓冲区。有人可以帮我解决这个问题吗？

Answer 1

您从未为 somebuf 分配任何内容：

char* somebuf;

因此，它不指向任何地方。

char* somebuf = new char[11];
somebuf[10] = '\0';          //  Not sure if it is necessary to null-terminate...
while(mp3.read(somebuf, 10)) //  Read the first 10 chars which are "I'm an MP3 file".
{
    //cout << somebuf;
}


//  and free it later
delete [] somebuf;

或者：

char somebuf[11];
somebuf[10] = '\0';          //  Not sure if it is necessary to null-terminate...
while(mp3.read(somebuf, 10)) //  Read the first 10 chars which are "I'm an MP3 file".
{
    //cout << somebuf;
}

Answer 2

初始化缓冲区：

char somebuf[10];
    while(mp3.read(somebuf, 10)) //Read the first 10 chars which are "I'm an MP3 file".
    {
        //cout << somebuf;
    }