String Split in C - c

Question

I want to split a String in C.
My String is defined by my Struct:
struct String
{
char *c;
int length;
int maxLength;
}
Then I have a function that does the splitting. Perhaps C has something that does this, but although I wanted my own, I have not found anything that will do it so far.
String ** spliter(String *s)
{
if(s == NULL)
return NULL;
// set of splitters: {'\n', ' '}
}
Input looks something like this: This is Sparta.
Then I want to return a pointer to each character array.
*p1 = This
*p2 = is
*p3 = Sparta.
If that makes any sense, I want an array of pointers, and each pointer points to a character array.
I will have to realloc the String as I increment the size of each character array. Probably my biggest problem is imagining how the pointers work.
Similar problem: c splitting a char* into an char**
So, how do I go about doing this?

Answer 1

#include <string>
#include <iostream>
#include <vector>
using namespace std;
int main()
{
string test = "aa aa bbc cccd";
vector<string> strvec;
string strtemp;
string::size_type pos1, pos2;
pos2 = test.find(' ');
pos1 = 0;
while (string::npos != pos2)
{
strvec.push_back(test.substr(pos1, pos2 - pos1));
pos1 = pos2 + 1;
pos2 = test.find(' ', pos1);
}
strvec.push_back(test.substr(pos1));
vector<string>::iterator iter1 = strvec.begin(), iter2 = strvec.end();
while (iter1 != iter2)
{
cout << *iter1 << endl;
++iter1;
}
return 0;
}

Answer 2

Have you looked at strtok? It should be possible to do this using strtok.

Answer 3

here is a exemple :
String ** spliter(String *s)
{
int i;
int j;
char *p1;
char *p2;
char *p3;
i = 0;
j = 0;
if(s == NULL)
return NULL;
p1 = malloc(sizeof(*p1) * strlen(s));
p2 = malloc(sizeof(*p2) * strlen(s));
p3 = malloc(sizeof(*p3) * strlen(s));
while (s[i] != ' ')
{
p1[j++] = s[i];
i++;
}
i++;
j = 0;
while (s[i] != ' ')
{
p2[j++] = s[i];
i++;
}
i++;
j = 0;
while (s[i] != '\0')
{
p3[j++] = s[i];
i++;
}
printf("%s\n", p1);
printf("%s\n", p2);
printf("%s\n", p3);
}

Answer 4

You're looking for strtok, check out man 3 strtok, or here if you're not on *nix.
You would use it like this: (Assuming that you can write the add_string code yourself.)
String ** spliter(String *s)
{
if(s == NULL)
return NULL;
String **return_strings = NULL;
char *delim = " \n";
char *string = strtok(s, delim);
int i = 0;
for(i = 0; add_string(return_strings, string, i) != -1; i++) {
string = strtok(NULL, delim);
}
return strings;
}
Note that if you need to save the original string (strtok modifies the string it works on), you'll need to call strdup on the original string, then operate on the copy.
EDIT: OP said he was having trouble thinking about the pointers. With the above code sample, add_string only has to worry about dealing with a string of characters, as opposed to an array of pointers to pointers to characters. So it might look something like this:
int add_string(String **strings, char *s, int len)
{
if(s == NULL)
return -1;
String *current_string = NULL;
strings = realloc(strings, sizeof(String) * (len + 1));
current_string = strings[len];
/* fill out struct fields here */
}

Answer 5

add strdup and strtok can work on a copy of the string. The split() call is more generic than the other spliter() examples, but does the same thing with strtok on a duplicate.
char **
split(char **result, char *w, const char *src, const char *delim)
{
int i=0;
char *p;
strcpy(w,src);
for(p=strtok(w, delim) ; p!=NULL; p=strtok('\0', delim) )
{
result[i++]=p;
result[i]=NULL;
}
return result;
}
void display(String *p)
{
char *result[24]={NULL};
char *w=strdup(p->c);
char **s=split(result, w, p->, "\t \n"); split on \n \t and space as delimiters
for( ; *s!=NULL; s++)
printf("%s\n", *s);
free(w);
}