Splitting function in C++ - c++

Question

I am trying to write a function that takes a string and a delimiter as an input and return an array of strings. For some reason, the following code runs into segmentation error. I am wondering what could be the problem?
char** split(string thing, char delimiter){
thing+='\0';//add null to signal end of string
char**split_string = new char*[100];
int i=0,j=0,l=0; //indexes- i is the ith letter in the string
// j is the jth letter in the lth string of the new array
int length = thing.length();
while (i < length){
if ((thing[i]!=delimiter && thing[i]!='\0')){
split_string[l][j]=thing[i];
j++;
}
else {
j=0; //reset j-value
l++;
}
i++;
}
return split_string;
}

Answer 1

After doing
char**split_string = new char*[100];
You still need to initialize each of the 100 char * pointers you created.
static const size_t str_len = 50; //assuming length will not exceed
for( size_t ix = 0 ; ix < 100 ; ++ix){
split_string[ix] = new char[str_len];
}
Also you need to make sure while writing to split_string you do not exceed the allocated memory in which case its 50 and you don't have splited strings more then 100.

Answer 2

Better split a std::string to std::vector<std::string>. Use the function below
#include <sstream>
#include <string>
#include <vector>
std::vector<std::string> split(std::string str, char delim) {
std::vector<std::string> result;
std::stringstream ss(str);
std::string token;
while (getline(ss, token, delim))
result.push_back(token);
return result;
}

Answer 3

1) Please allocate memory for each substring (something like char[l] = new char[100]) when ever you find a new substring.
As you do not know the number of substring in the beginning itself, please consider using vector. consider using vector < string > split_string. In the loop when ever you find a new sub string you just push that string in the vector. In the end, you will have all the splitted strings in the vector.

Answer 4

Each char * has to be individually initialized like this.
int len = 100;
char**split_string = new char*[len]; // len holds the number of pointers
for(int k = 0; k < len; k++) {
split_string[k] = new char[500]; // holds len of string (here Max word size is considered 500)
}
In C++, sticking to the usage of std::string would be more recommended to reduce complexity and increase readablity.
Your code will fail to catch hold of the last substring as you are breaking out of while-loop just before finding \0. To fix that you need to change the while (i < length) to while (i <= length).
Using vector < string >:
vector<string> split(string thing, char delimiter){
int len = 100;
vector<string> v;
char c[500];
int i=0,j=0;
int length = thing.length();
while (i <= length){
if ( thing[i] != delimiter && thing[i] != '\0') {
c[j]=thing[i];
j++;
}
else {
c[j] = '\0';
v.push_back(c);
memset(c, 0, sizeof c);
j = 0;
}
i++;
}
return v;
}
Demo.