100 lines
2.0 KiB
C
100 lines
2.0 KiB
C
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#include <stdio.h>
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#include <stdlib.h>
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struct MyStruct
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{
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int NoItems;
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int max;
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float average;
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};
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int main()
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{
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struct MyStruct MyRecord;
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FILE *fptr;
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int ArrayData[100];
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int items = 0;
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int sum = 0;
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int i;
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int AValue;
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/* Write this file to disk - binary format, usual error checking */
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fptr = fopen ("strdata.dat","wb");
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if ( fptr == NULL )
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{
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printf ("\nError creating file - aborting ");
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exit (0);
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}
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/* Pop some dummy data into our structure */
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MyRecord.NoItems = 0;
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MyRecord.max = 0; ;
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MyRecord.average = 0;
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/* This line does the writing of the structure */
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fwrite ( &MyRecord, sizeof(struct MyStruct), 1, fptr);
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/* Populate the array */
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for ( i = 0 ; i < 100 ; i++)
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{
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ArrayData[i] = i;
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if ( ArrayData [i] > MyRecord.max)
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MyRecord.max = ArrayData[i];
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sum = sum + ArrayData[i];
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items++;
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}
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/* This line does the writing of the Array */
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fwrite ( &ArrayData[0], sizeof(int),100, fptr);
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/* Update the values in the structure */
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MyRecord.NoItems = items;
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MyRecord.average= (float)sum / (float)items;
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/* rewind the file to write the structure again */
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fseek(fptr, SEEK_SET, 0);
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rewind (fptr);
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/* This line does the writing of the structure */
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fwrite ( &MyRecord, sizeof(struct MyStruct), 1, fptr);
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/* And close */
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fclose (fptr);
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/* To read the data we would use */
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fptr = fopen ("strdata.dat","rb");
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if ( fptr == NULL )
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{
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printf ("\nError opening input file - aborting ");
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exit (0);
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}
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/* This line does the reading */
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fread ( &MyRecord, sizeof(struct MyStruct), 1, fptr);
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printf ("No. items in the file = %d\n", MyRecord.NoItems);
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printf ("Maximum = %d\n", MyRecord.max);
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printf ("Average is = %.2f\n", MyRecord.average);
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// Get how far to move for thr 10th item
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long Posn = sizeof (struct MyStruct) + (9 * sizeof(int));
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// Move
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fseek(fptr, Posn, SEEK_SET);
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// Read value
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fread ( &AValue, sizeof(int),1 , fptr);
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printf ("The 10th value is %d", AValue);
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/* And close */
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fclose (fptr);
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/* All Done */
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return 0;
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}
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