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Purpose |
Reads a specified amount of data from a file | |
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Old names |
#define _vnread tf_read | |
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Syntax (CCOWN) |
unsigned tf_read(int file_handle, void * data, unsigned bytes) | |
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Syntax (DP4DBAPI) |
dp4_file_size dp4_sf_read(FCONN * fconn,void * buffer,dp4_file_size nr_bytes); | |
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Parameters |
int file_handle |
File handle of file from which to read, obtained earlier with a successful call to tf_open() or sf_open() |
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Parameters |
FCONN * fconn |
File handle of file from which to read, obtained earlier with a successful call to dp4_sf_open() |
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ANY* data |
Pointer to buffer to hold data that is read |
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unsigned bytes |
Number of bytes to read from file |
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Description |
The tf_read() and sf_read() functions read the specified number of bytes from a file into a buffer .The sf_read() function calls the file handling support in the database manager, and the tf_read() function calls the file handling support in the terminal manager. You must not call an sf_ function with a handle obtained with tf_open(), or a tf_ function with a handle obtained with sf_open(). | |
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Return values |
Returns the number of bytes read. This may be less than the requested number when the end of file is reached.
For dp4_sf_read only. If an error occurs when dp4_sf_read() is called, then the return value will be the number of bytes that had been read when the error occurred: If you do not have an error callback installed, then you will need to cal dp4_error_status() to check whether an error occurred. | |
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See also |
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