Convert C code to Matlab code for reading binary file

I'm looking for help reading a binary file in the most efficient way (fast). Here is the C-code. Thanks.

#define MAX_LAYERS 100

typedef struct

{

char string[1000];

} STRINGARRAY_STRUCT;

typedef struct

{

double rangeFinals;

double crossFinals;

STRINGARRAY_STRUCT time[MAX_LAYERS]; // Sample: xx:xx:xx

double dir[MAX_LAYERS]; // degrees

double speed[MAX_LAYERS]; // knots

int flagSpeed[MAX_LAYERS]; // flag speed

int flagDir[MAX_LAYERS]; // flag direction

int flagTime[MAX_LAYERS]; // flag time

int percentTraversed;

int year[MAX_WIND_LAYERS];

int jDay[MAX_WIND_LAYERS];

} CURRENT_STRUCT;

typedef struct

{

char string[1000];

} STRINGARRAY_STRUCT;

int main (int argc, char **argv)

{

FILE *fp;

CURRENT_STRUCT winds;

fp = fopen (FileName, "rb");

if (fp != NULL)

{

fread (&winds, sizeof(CURRENT_STRUCT), 1, fp);

fclose (fp);

}

}

[Mike D.]

I allocated a blank structure like this:

s = struct('DR',0,'CR',0,'layers',char(zeros(100,100)), ...

'winddir',NaN(100,1),'windspeed',NaN(100,1), ...

'flagSpeed',uint8(0),'flagDir',uint8(0),'flagTime',uint8(0), ...

'traversed',uint8(0),'year',uint8(ones(100,1)),'jday',uint8(ones(100,1)));

But what is the fread syntax after doing fopen?

Answer 1

[Les Beckham]

Your Matlab struct doesn't match the definition in the C code. For example, the third element is a char array of 100x1000 in the C code and a 100x100 array in the Matlab code, flagDir and flagTime are arrays in the C code (of some unknown length, since you didn't show the definition of MAX_WIND_LAYERS), but scalar in the Matlab code. Also, some of the names don't match, which may or may not be an issue.

If you provide a sample of the data file it will be easier to get an accurate answer.

I think you are going to have to read the struct in pieces and copy those pieces into your struct.

For example:

rangeFinals = fread(fp, 1, 'double');
crossFinals = fread(fp, 1, 'double');
time = fread(fp, [100, 1000], 'char');
...
s.rangeFinals = rangeFinals;
s.crossFinals = crossFinals;
...

[Mike D.]

Thanks for the comments. Yea, I noticed the 100x1000 issue and the different names and MAX_WIND_LAYERS is supposed to be MAX_LAYERS. These things are easy fixes. I'm more concerned about the overall structure and how to efficiently read the data. I currently have it like you say:

s(i).DR = fread(app.fileID,1,'double');

s(i).CR = fread(app.fileID,1,'double');

for j = 1 : 100

s(i).layers(j,:) = fread(app.fileID,1000,'char');

end

s(i).dir = fread(app.fileID,100,'double');

s(i).speed = fread(app.fileID,100,'double');

s(i).flagSpeed = fread(app.fileID,100,'uint8');

s(i).flagDir = fread(app.fileID,100,'uint8');

s(i).flagTime = fread(app.fileID,100,'uint8');

s(i).transversed = fread(app.fileID,1,'uint8');

s(i).year = fread(app.fileID,100,'uint8');

s(i).jday = fread(app.fileID,100,'uint8');

I just thought there might be an easier way (less code) and faster more efficient way, such as a one-liner with fread given the structure format.

[Les Beckham]

Unfortunately, I don't think you can do it all at once in Matlab like you can in C.