finding substring c++ [duplicate] - c++

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How to split a string?
Hi,
I have a string say "1,0,1", how can i get the substring separated by comma operator.

Answer 1

C++ doesn't have a built in function for doing exactly this. However, it can be implemented using either the std::string::find_first_of member function, or the non-member std::find.
Here's an example using the latter:
#include <string>
#include <vector>
#include <algorithm>
// given a string str, split it on every occurrence of the character delim
std::vector<std::string> tokenize(std::string str, char delim) {
// store the results in a vector of strings
std::vector<std::string> tokens;
std::string::iterator end = str.end();
std::string::iterator left = str.begin();
for (;;) {
// find the next occurrence of the delimiter
std::string::iterator right = std::find(left, end, delim);
// create a string from the end of last one up until the one we just foun
tokens.push_back(std::string(left, right));
// if we reached the end of the string, exit the loop
if (right == end) { break; }
// otherwise, start the next iteration just past the delimiter we just found
left = right + 1;
}
return tokens;
}
// test program
int main() {
std::string str = "foo, bar, baz";
std::string str2 = "foo, bar, baz,";
std::string str3 = "foo";
std::string str4 = "";
std::string str5 = ",";
std::vector<std::string> tokens = tokenize(str, ',');
std::vector<std::string> tokens2 = tokenize(str2, ',');
std::vector<std::string> tokens3 = tokenize(str3, ',');
std::vector<std::string> tokens4 = tokenize(str4, ',');
std::vector<std::string> tokens5 = tokenize(str5, ',');
}
Of course there are a lot of border cases to handle, and this implementation might not do exactly what you want, but it should give you a starting point.

Answer 2

another way of doing this is by using strtok. This is a old c way but it still applies to the problem.
using <vector>
using <string>
char* token, line[512];
std::string tokenStr;
std::string lineStr = "0, 1, 2";
std::vector<std::string> commaSplit;
strcpy ( line, lineStr.c_str());
//Remove spaces and find the first instance of ','
token = strtok( line, " ," );
while(token != NULL)
{
//Copy the token to a string
tokenStr = token;
//Add the token to the vector
commaSplit.push_back(token);
//Find next instance of the ,
token = strtok(NULL, " ,");
}

Answer 3

Search google for an algorithm to explode or tokenize your string. It's trivial.
You can also check out the documentation and use available tools : http://www.cplusplus.com/reference/string/string/
A simple implementation could be :
void tokenize(const string & text, vector<string> & tokens, char delim)
{
size_t length = text.size();
string token = "";
for(size_t i=0;i<length;i++)
{
if(text[i] != delim)
{
token += text[i];
}
else
{
if(token.size() > 0)
{
tokens.push_back(token);
}
token = "";
}
}
tokens.push_back(token);
}