Chapter 3 Terminal Specific Function Library
195
read
Purpose
To read a specified number of bytes from a DAT file.
Syntax
int read (int fd, char *buffer, int count);
int fd; /* file handle of the target DAT file */
char *buffer; /* pointer to a buffer where data is read into */
int count; /* number of bytes to be read */
Example
if ((byte_read = read (fd, buffer, 80)) == -1) puts ("read error!\n");
Description
This routine reads a number of bytes (
count
) from a DAT file (
fd
) into the
character array
buffer
.
Reading of data starts at the current position of the file pointer, which is
incremented accordingly when the operation is completed.
Return
If successful, it returns the number of bytes actually read from the file.
On error, it returns -1.
An error code is set to the global variable fErrorCode to indicate the error
condition encountered. Below are possible error codes and their interpretation.
Error Code
Interpretation
2
File specified by
fd
does not exist.
4
File specified by
fd
is not a DAT file.
7
Invalid file handle.
8
File not opened.
9
The value of
count
is negative.
See Also
readln, write, writeln
readln
Purpose
To read a line (null-terminated string) from a DAT file.
Syntax
int readln (int fd, char *buffer, int max_count);
int fd; /* file handle of the target DAT file */
char *buffer; /* pointer to a buffer where data is read into */
int max_count; /* maximum number of bytes to be read */
Example
readln (fd, buffer, 80);
Description
This routine reads a null-terminated string from a DAT file (
fd
) into the
character array
buffer
.
Characters are read until end-of-file or a null character (\0) is encountered, or
the total number of character read equals the number specified by
max_count
.
Содержание Optimus R
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