Now what exactly are you having a problem with ?
a) the first being faster than the second in case the file doesn't exist ?
- the answer for that is that you're not doing error handling
in the first program; fopen() FAILS on you and actually doesn't
do any work, hence it's faster.
- if you modify the second so that it doesn't pass O_CREAT, then
it's always faster.
b) the second being faster in case the file exists ?
- as explained, fopen() does more than open; it _MUST_ take
longer.
Btw, the test programs as they are don't even compile. I've attached
versions that do.
Best regards,
FrankH.
On Mon, 15 Jan 2007, gaurav kadyan wrote:
The two test cases
1:
int main()
{
struct timeb time1,time2;
unsigned long timeTaken;
FILE * fp;
ftime(&time1);
fp = fopen("abcd.txt","r");
timeb(&time2);
timeTaken = (1000 * (time2.time - time1.time)) + time2.millitm - time1.millitm;
printf("time taken %ld",timeTaken);
return 1;
}
2:
int main()
{
struct timeb time1,time2;
unsigned long timeTaken;
int fd;
ftime(&time1);
fd = open("abcd.txt",O_CREAT);
timeb(&time2);
timeTaken = (1000 * (time2.time - time1.time)) + time2.millitm - time1.millitm;
printf("time taken %ld",timeTaken);
return 1;
}
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#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
int main()
{
hrtime_t t1, t2;
unsigned long timeTaken;
FILE * fp;
t1 = gethrtime();
fp = fopen("abcd.txt","r");
t2 = gethrtime();
if (fp == NULL)
printf("fopen() failed, errno = %d\n", errno);
timeTaken = (long)(t2 - t1);
printf("time taken %ld\n",timeTaken);
return 1;
}
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
int main()
{
hrtime_t t1, t2;
unsigned long timeTaken;
int fd;
t1 = gethrtime();
fd = open("abcd.txt", 0);
t2 = gethrtime();
if (fd < 0)
printf("open() failed, errno = %d\n", errno);
timeTaken = (long)(t2 - t1);
printf("time taken %ld\n",timeTaken);
return 1;
}
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