mdefoor wrote:
> I've written the following sample to split a string into chunks. Is
> this the right approach or is there perhaps a better way to accomplish
> getting chunks of a string?
There is a better way. sprintf() and strcat() are expensive, especially
when you can explicitly do it yourself.
>
> #include <stdio.h>
> #include <string.h>
>
> #define BUFSIZE 10
>
> int main(int argc, char *argv[]) {
> int i;
> int nbr;
> char buff[256];
> char tmpChr[1];
/* what in the world is this? Get rid of the above and use char *tmpChr;
at the very least */
> char *buffer;
>
> sprintf(buff, "%s", "this is a longer buffer");
> buffer = strdup(buff);
>
> char tmpBuff[strlen(buffer) + 1];
/* tsk, tsk. declarations belong at the top of the function. */
> *tmpBuff = '\0';
>
> i = 0;
> nbr = 0;
>
> printf("buffer = %s len = %d\n", buffer, strlen(buffer));
>
> do {
> if (i < BUFSIZE) {
> sprintf(tmpChr, "%c", buffer[nbr]);
> strcat(tmpBuff, tmpChr);
> i++;
> nbr++;
> if (nbr == strlen(buffer)) {
> printf("--%s-- i = %d nbr = %d\n", tmpBuff, i, nbr);
> }
> }
> else {
> printf("--%s-- i = %d nbr = %d\n", tmpBuff, i, nbr);
> i = 0;
> *tmpBuff = '\0';
> }
> } while (buffer[nbr] != '\0');
> }
>
You seem to be fairly new at programming in c so pay close attention to
my comments as they will help you (unless I've made a typo somewhere - I
compiled this and it worked correctly, but it's late so anything could
happen).
#include <stdio.h>
#include <string.h>
#include <stdlib.h> /* exit() and friends */
#define BUFSIZE 10
int chunk_split(const char *src, char **dest, int len);
/**
* Split a string into several lines with each line being
* no more than len characters.
*
* NOTE: There are actually several different ways of doing
* this. For instance, we could make a copy of src and use
* *tmp++ = *srccpy++ instead of *tmp++ = src[i]. Both would
* do exactly the same thing and most modern compilers will
* optimise it either way. Personal preference I suppose.
*
* @param src Source buffer
* @param dest Destination buffer
* @param len Maximum length of a line
* @return 0 on success, nonzero indicates error
*/
int chunk_split(const char *src, char **dest, const int len)
{
char *tmp = *dest;
int i = 0;
int j = 0;
int srclen = strlen(src);
for(i = 0; i < srclen; i++)
{
for(j = 0; j < len; j++)
*tmp++ = src[i++];
*tmp++ = '\n';
i--;
}
*tmp++ = '\0';
return(0);
}
int main(int argc, char **argv)
{
int length = 0;
char *buffer = NULL;
/* you can get your source buffer from anywhere. this is
* easier for testing, imho. */
if(argc != 2)
{
printf("Usage: %s \"some string\"\n", argv[0]);
exit(EXIT_FAILURE);
}
/* plenty of room for our added newlines */
length = (strlen(argv[1]) + (strlen(argv[1]) / 10));
/* always test your calls to malloc otherwise gremlins
* might come and take you away to SIGSEGVland. */
if((buffer = malloc(length + 1)) == NULL)
{
perror("malloc");
exit(EXIT_FAILURE);
}
chunk_split(argv[1], &buffer, BUFSIZE);
/* tada */
printf("before: %s\n----------\n%s\n----------\n", argv[1], buffer);
free(buffer);
return(0);
}
You gave it an honest attempt, and for that I took the time to rewrite
this into something a little more usable. Hope it helps.
Joe
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