Read binary file into structure

Add a comment. Active Oldest Votes. Improve this answer. DanielHallel What do you mean by a "real" binary file? Why do you want to avoid using fwrite? DanielHallel Now go read its documentation, fwrite doesn't re create the file if you tell it not to do so.

Mark Wilkins Mark Wilkins Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Stack Gives Back Safety in numbers: crowdsourcing data on nefarious IP addresses. Therefore, specify the skip argument as 2. Return to the beginning of the file using frewind. If you read 4 bits at a time on a little-endian system, your results appear in the wrong order.

Read the data 4 bits at a time as before, but specify a big-endian ordering to display the correct results. File identifier of an open binary file, specified as an integer. Before reading a file with fread , you must use fopen to open the file and obtain the fileID. Dimensions of the output array, A , specified as Inf , an integer, or a two-element row vector.

Class and size in bits of the values to read, specified as a character vector or a string scalar in one of the following forms. Optionally the input specifies the class of the output matrix, A.

Read N values before skipping the number of bytes specified by the skip argument. The following table shows possible values for source and output. Set encoding with fopen. For most values of source , if fread reaches the end of the file before reading a complete value, it does not return a result for the final value.

However, if source is bit n or ubit n , then fread returns a partial result for the final value. Data Types: char string. Number of bytes to skip after reading each value, specified as a scalar. If you specify a precision of bit n or ubit n , specify skip in bits.

Use the skip argument to read data from noncontiguous fields in fixed-length records. Order for reading bytes in the file, specified as a character vector or a string scalar. Specify machinefmt as one of the values in the table that follows. For bit n and ubit n precisions, machinefmt specifies the order for reading bits within a byte, but the order for reading bytes remains your system byte ordering.

By default, all currently supported platforms use little-endian ordering for new files. Existing binary files can use either big-endian or little-endian ordering. File data, returned as a column vector. If you specified the sizeA argument, then A is a matrix of the specified size. Data in A is class double unless you specify a different class in the precision argument. The input argument precision must be a constant. The source and output classes that precision specifies cannot have these values: 'long' , 'ulong' , 'unsigned long' , 'bit n ' , or 'ubit n '.

If the source or output that precision specifies is a C type, for example, int , then the target and production sizes for that type must:. The code reads the first several Strings and even the first 2 Integers ok, But after the Crystal Material string is read, the next Double for the Laser Wavelength and all data after that is wrong.

I've tried to adjust the length of the Crystal Material up and down by 1 , 35 and 37, the same string is printed and it has no effect on the following Double value for the laser wavelength. I can read all bytes in and use the BitConverter method to convert the same byte array position and I get a different number, which I believe is correct I can brute force this problem with the BitConverter method, but I'd really like to understand the general solution to reading in a structure Code Block.

Dim Label As String. Dim Version As Integer. Dim sDate As String. Dim FileFormat As Integer '. Dim FileType As String. Dim Annotate As String. Dim InstrumentModel As String. Dim SpareNe As String. Dim sEnd As String ' char End[4];. End Structure. SizeOf header. Dim buf len - 1 As Byte. Dim readCount As Integer. AllocHGlobal len ' allocate len bytes of memory. PtrToStructure mem, header. End Function.

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