File

Constructor

Parameters

• mode: The argument mode is a string beginning with one of the following sequences
  • : open text file for reading. The stream is positioned at the beginning of the file.
  • truncate file to zero length or create text file for writing. The stream is positioned at the beginning of the file.
  • open for appending (writing at end of file). The file is created if it does not exist. The stream is positioned at the end of the file.

  The mode string can also include the letter b as a last character. Adding the b is used if you do I/O to a binary file (but note that The b is ignored on all POSIX conforming systems, including Linux).

• swap If true then byte swaping is forced when using the mget and mput functions.
• xdr If true then reading and writing is used using xdr.

Description
The File data type is used for file I/O operations.

Operations on File objects

• F.close[]: close the file stream.
• F.putstr[str]: outputs a string.
• F.put[M,type=’string’] outputs the contents of real matrix M using the type parameter as a conversion specifier. The type argument can be chosen among "l", \verb”i”+, "s", "ul", "ui", "us", "d", "f", "c","uc" for writing respectively a long, an int, a short, an unsigned long, an unsigned int, an unsigned short, a double, a float, a char and an unsigned char. The bytes which are read are automatically swapped if necessary (by checking little-endian status). This default swapping mode can be suppressed by adding a flag in the mopen function. It is also possible to read in little-endian or big-endian mode by adding a ’l’ or ’b’ character at the end of a type specification. For example ’db’ can be used to read a double in big-endian mode.
• F.get[n=val,type=’string’]: reads n values of type given by type (see the above put method for type specification). and returns the values in a vector of size n.
• F.getstr[n=val]: reads n bytes and returns the a string.
• F.eof[]: returns %t if an end-of-file was encountered.
• F.seek[value,str]: sets the file position indicator. The new position, measured in bytes, is obtained by adding offset bytes to the position specified by ˙verb+str+. If str is set to ’set’, cur, ’end’ the offset is relative to the start of the file, the current position indicator, or end of file, respectively. Successful call clears the end of file indicator.
• F.tell[]: returns the current value of the file position indicator.
• F.clearerr[]: clears any previously raised error.
• F.error[]: returns %t if an error was encountered during previous read/write operations
• [M,S]F.get_matrix[format=’string’]: read a scalar matrix from file current position. First lines can be non-numeric and are then returned in S. The read stops when current line read is not compatible with previous ones. An optional format to be used for reading each matrix entry can be given.
• S=F.get_lines[n]: acquires n lines from the file stream F and returns the result in a string matrix. If n is omitted or negative it is assumed to be equal to one.
• S=F.get_smatrix[]: read the whole file contents from current position and return a column string vector. Each line read giving a row of the column vector.
• F.put_matrix[M,format=’string’,sep=’string’,title=S]: output matrix contents in a file using the given format for each element and the string given by sep as separator. If title is given its contents is outputed in the file before the matrix. Default value for format is the defualt format used in nsp interactive output and defaut separator is a white space.
• F.put_smatrix[S]: output the contents of a string matrix in file F the string matrix is explored columnwise (i.e equivalent to S(:)).
• F.print[Obj,as_read=boolean,depth=integer, indent=integer,latex=boolean,name=string,table=boolean]: see the print function for a description of optional arguments.
• F.printf[format,arg1,...,argn]: Similar to the C fprintf function.

• fopen open a file for I/O operations returning a File object.
• is_little_endian checks the little-endian machine specification.
• getfile(fname): gets the contents of ascii file given by fname in a string column vector.
• putfile(fname,S): put the contents of a string matrix in file named fname. If the file already existed its contents is replaced if not it is created.

Examples

  Examples  

See also unique (??) setdiff (??)

Authors jpc