matlab中二进制文件中的浮点读取错误

Question

我试图在matlab中读取一个数组浮点，存储在二进制文件中。最初的文件是用C++代码创建的，通过内存映射技巧。

#include <iostream>
#include <sys/types.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
int main() 
{
    const char* filePath   = "test_file.dat";
    const size_t NUM_ELEMS = 11;

    /* Write the float array to the binary file via memory mapping */
    const size_t NUM_BYTES = NUM_ELEMS * sizeof(float);//array of the 11 floats;    
    int fd = open(filePath, O_RDWR | O_CREAT | O_TRUNC, 0);//open file
    lseek (fd, NUM_BYTES - 1, SEEK_SET);//stretch the file size
    write(fd, "", 1);//write empty string at the end of file
    float* mappedArray = (float*)mmap(0, NUM_BYTES, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);//map array to the file

    for(size_t i = 0; i < NUM_ELEMS; ++i)//fill array
        mappedArray[i] = static_cast<float>(i) / 10.0f;

    munmap(mappedArray, NUM_BYTES);
    close(fd);

    /* Test reading the recorded file*/    
    std::ifstream fl(filePath, std::ios::in | std::ios::binary);
    float data = 0.0f;
    for(size_t i = 0; i < NUM_ELEMS; ++i)
    {
        fl.read(reinterpret_cast<char*>(&data), sizeof(data)); 
        std::cout<<data<<"\n";
    }

    fl.close();
}

function out = readDataFromFile()
    fid = fopen('test_file.dat','r','b'); 
    out = fread(fid, 11, '*float');  
    fclose(fid);
end

我想要注意的是，如果我写了uint8_t（或未签名的char）数组，那么从matlab读取这个文件就成功了。我在MATLAB中做错了什么？

我的系统-64位Ubuntu 13.04,C++编译器-gcc 4.8,MATLAB-2013A

Answer 1

通过替换来解决问题

fid = fopen('test_file.dat','r','b');

在

fid = fopen('test_file.dat','r');