How to Split a String by Multiple Delimiters in C++?

In C++, while working with string manipulation we may sometimes need to split a string into substrings based on multiple delimiters. In this article, we will learn how to split a string by multiple delimiters in C++.

For Example,

Input:
string inputString= "Hello,World;This|is.GeeksForGeeks";
string delimiters = ",;.|";

Output:
Hello
World
This
is
GeeksForGeeks

Split a String into Words by Multiple Delimiters in C++

To split a std::string by multiple delimiters, we can use std::string::find_first_of to search the delimiters in a string with the combination of std::string::substr to extract the substrings.

Approach

1. Start with startPos = 0 and endPos = 0, run a loop until endPos is not equal to string::npos
2. Use std::string::find_first_of to find the position of the first occurrence of any delimiter.
3. If found, use std::string::substr to extract the substring between startPos and the delimiter position found by find_first_of and add it to result.
4. If not found, extract the substring from startPos to the end of the string and add it to result also set endPos to string::npos to exit the loop.
5. Repeat the process until the end of the string is reached.

C++ Program to Split a String by Multiple Delimiters

The below example demonstrates how we can split a given string by multiple delimiters in C++.

C++

// C++ Program to split the string by miltiple delimiters

#include <iostream>
#include <string>
#include <vector>
using namespace std;

// Function to split a string by multiple delimiters
vector<string> splitStringByDelimiters(string& inputString,
                                       string& delimiters)
{

    vector<string>
        result; // Vector to store the split substrings
    int startPos = 0;
    int endPos = 0;

    // Loop until endPos is not equal to string::npos
    while ((endPos = inputString.find_first_of(delimiters,
                                               startPos))
           != string::npos) {

        if (endPos != startPos) { // Checking if the
                                  // substring is non-empty
            result.push_back(inputString.substr(
                startPos, endPos - startPos));
        }

        startPos
            = endPos + 1; // Update startPos to the position
                          // after the delimiter
    }

    // Extract the substring from startPos to the end of the
    // string and add it to result
    if (startPos != inputString.length()) {
        result.push_back(inputString.substr(startPos));
    }
    return result;
}

int main()
{

    // string to be splitted
    string inputString
        = "Hello,World;This|is.GeeksForGeeks";

    // multiple delimiters
    string delimiters = ",;.|";

    // calling the function to split the string using
    // multiple delimiters
    vector<string> substrings
        = splitStringByDelimiters(inputString, delimiters);

    // Displaying the string after splitiing
    for (const auto& substring : substrings) {
        cout << substring << endl;
    }

    return 0;
}

Output

Hello
World
This
is
GeeksForGeeks

Time Complexity: O(n)
Auxiliary Space: O(n) , here m is the number of substrings in the result vector.