012
12.11.2003, 14:03 Uhr
virtual
Sexiest Bit alive
(Operator)
|
Meine Gedanken dazu sind:
| C++: |
#include <stdio.h>
#include <stdlib.h> /* Required for demo program only */
/** filecopy
* Copies <source> to <target>
* @param <source> Name of the source file
* @param <target> Name of the target file
* @return 0, if succeed, any other return code signs an error:
* -1: <source> cannot be opened
* -2: <target> cannot be opened
* -3: Failed to read from <source>
* -4: Failed to write to <target>
*/
int filecopy(
const char* source,
const char* target)
{
int ret = 0;
char buffer[8192];
FILE* s = NULL;
FILE* t = NULL;
size_t len;
/*
* Open source
*/
s = fopen(source, "rb");
if (NULL == s)
{
return -1;
}
/*
* Open target
*/
t = fopen(target, "wb");
if (NULL == t)
{
fclose(s);
return -2;
}
/*
* Turn off buffering to avoid useless copying
* (our buffer is large enough)
*/
setbuf(s, NULL);
setbuf(t, NULL);
/*
* Loop to copy file
*/
do
{
/*
* Read next portion
*/
len = fread(buffer, 1, sizeof(buffer), s);
if (sizeof(buffer)!=len && !feof(s))
{
ret = -3;
break;
}
/*
* Write the fetched portion
*/
if (0 < len)
{
if (len != fwrite(buffer, 1, len, t))
{
ret = -4;
break;
}
}
} while (sizeof(buffer)==len);
/*
* Close the files
*/
fclose(t);
fclose(s);
/*
* Remove target, if an error took place
*/
if (0 != ret)
{
remove(target);
}
return ret;
}
/** Demo
* A poor mans copy that copies a file to an other.
*/
int main(
int argc,
char** argv)
{
int fc_ret;
/*
* Check command line
*/
if (argc != 3)
{
fprintf(stderr,
"error: %s: bad commad line.\n"
"usage: %s <source> <target>\n",
*argv,
*argv);
exit(EXIT_FAILURE);
}
/*
* Copy files
*/
fc_ret = filecopy(argv[1], argv[2]);
if (0 != fc_ret)
{
fprintf(stderr,
"error: %s: cannot copy %s to %s: ",
argv[0],
argv[1],
argv[2]);
switch (fc_ret)
{
case -1:
fprintf(stderr,
"cannot open %s for reading.\n",
argv[1]);
break;
case -2:
fprintf(stderr,
"cannot open %s for writing.\n",
argv[2]);
break;
case -3:
fprintf(stderr,
"cannot read from %s.\n",
argv[1]);
break;
case -4:
fprintf(stderr,
"cannot write to %s.\n",
argv[2]);
break;
default:
fprintf(stderr,
"unknown error.\n");
break;
}
exit(EXIT_FAILURE);
}
return EXIT_SUCCESS;
}
|
Durch ausschalten des Bufferings sollte sich das 3 Malige Kopieren auf 1 Mal reduzieren lassen...
--
Gruß, virtual
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Ich eß' nur was ein Gesicht hat (Creme 21) |
