fread(3C)
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fread function
Read a number of records from a file.
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Calling Sequence
#include <stdio.h>
char *buffer;
FILE *fp;
int numrec, numbyt, numread;
numread = fread(buffer, numbyt, numrec, fp);
where buffer is a byte pointer to a user-provided buffer.
numbyt is the number of bytes per record.
numrec is the number of records to read.
fp is a pointer to a FILE stream.
numread is the number of records actually read.
Description
The fread function reads records from a specified file. It reads
the number of records you specify that are of the length you
specify. The include file stdio.h defines this function.
Since the hardware representation for byte pointers differs from
that of word pointers, dg_stdio.h defines a macro fread to force
the first argument to a byte pointer.
Returns
The function returns the number of whole records that it read
before an error or end of file occurred. This function returns 0
if it read no records.
Related Functions
See also the fwrite function.
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fread(3C)
Example
/* Program test for the fread() function */
#include <stdio.h>
FILE *fopen(), *fp;
char buffer[100];
int atoi(), numrec, numbyt, numread;
main(argc, argv)
int argc;
char *argv[];
{
fp = fopen(argv[1], "r");
numrec = atoi(argv[2]);
numbyt = atoi( argv[3] );
printf("Number of records read = %d\n",
numread = fread(buffer, numbyt, numrec, fp));
}
A call to the program test with the valid filename input_nos,
which contains 0123456789, and the arguments 8 and 2 generates
the output
Number of records read = 5
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