How to use stringstream to separate comma separated strings [duplicate]

Question

This question already has answers here:

How do I iterate over the words of a string? (85 answers)

Closed 6 years ago.

I've got the following code:

std::string str = "abc def,ghi";
std::stringstream ss(str);
string token;
while (ss >> token)
{
 printf("%s\n", token.c_str());
}

The output is:

abc
def,ghi

So the stringstream::>> operator can separate strings by space but not by comma. Is there anyway to modify the above code so that I can get the following result?

input: "abc,def,ghi"

output:
abc
def
ghi

• pmr: Splitting a string in C++ contains everything a human should know about splittin strings in C++
• VLL: Second answer in the duplicate target also answers this question: stackoverflow.com/a/236803/2527795

Answer 1

#include <iostream>
#include <sstream>
std::string input = "abc,def,ghi";
std::istringstream ss(input);
std::string token;
while(std::getline(ss, token, ',')) {
 std::cout << token << '\n';
}

abc
def
ghi

• Dmitry Gusarov: Why do you guys always use std:: and full namespaces instead of using namespace? Is there specific reasoning for this? I just always find it as a very noisy and had-to-read syntax.
• jrok: @DmitryGusarov It's a habit and a good practice. It doesn't matter in short examples, but using namespace std; is bad in real code. More here.
• Dmitry Gusarov: ah, so it sounds like the problem caused by c++ ability to have a method outside of a class. And probably this is why it never lead to problem in C# / Java. But is it a good practice to have a method outside of a class? Modern languages like Kotlin don't even allow static methods.
• akmin04: In Kotlin, you can declare functions inside companion object inside classes which are basically static methods.
• Jay: This is short and readable which is great, but is this the fastest way to do it in c++?

Answer 2

#include <iostream>
#include <string>
#include <sstream>
using namespace std;
int main()
{
 std::string input = "abc,def, ghi";
 std::istringstream ss(input);
 std::string token;
 size_t pos=-1;
 while(ss>>token) {
 while ((pos=token.rfind(',')) != std::string::npos) {
 token.erase(pos, 1);
 }
 std::cout << token << '\n';
 }
}

• Ashok Arora: This code isn't correct, it generates abcdef \n ghi as output.