eddyhalim
asked on
how to delete one record in a structure?
can somebody tellme how to delete a one record in a file?
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ozo
Do you care about preserving the order of the other records?
ASKER
please give me the step and the source for example.
Another solution would be to have a member of the structure defining the state of the record, so that you can mark it deleted ... Like the old dBase II files... A some point you can then use FuzzyLogic's suggestion to compact the file.
... Like the WinWord .DOC files... (Got bless Macro$oft ;)
#include <stdio.h>
#include <stdlib.h>
typedef struct {
long l;
char s[20];
} Unit; // Your structure
void main() {
FILE *fin;
FILE *temp;
Unit u;
const char filename[] = "Whatever.dat";
fin = fopen(filename, "r");
temp = tmpfile();
if (fin==NULL || temp==NULL) {
exit(-1); // Something wrong.
}
while (fread((void *)&u, sizeof(Unit), 1, fin)>0)
if (1) // Your test here
fwrite((void *)&u, sizeof(Unit), 1, temp);
fclose(fin);
fin = fopen(filename, "w");
rewind(temp);
while (fread((void *)&u, sizeof(Unit), 1, temp)>0)
fwrite((void *)&u, sizeof(Unit), 1, fin);
fclose(fin);
fclose(temp); // tempfile is erased when closed.
}
#include <stdlib.h>
typedef struct {
long l;
char s[20];
} Unit; // Your structure
void main() {
FILE *fin;
FILE *temp;
Unit u;
const char filename[] = "Whatever.dat";
fin = fopen(filename, "r");
temp = tmpfile();
if (fin==NULL || temp==NULL) {
exit(-1); // Something wrong.
}
while (fread((void *)&u, sizeof(Unit), 1, fin)>0)
if (1) // Your test here
fwrite((void *)&u, sizeof(Unit), 1, temp);
fclose(fin);
fin = fopen(filename, "w");
rewind(temp);
while (fread((void *)&u, sizeof(Unit), 1, temp)>0)
fwrite((void *)&u, sizeof(Unit), 1, fin);
fclose(fin);
fclose(temp); // tempfile is erased when closed.
}
eddyhalim - you must have cought me in a good day... Usually I don't write code for 5pt.