This tutorial will go through how to iterate over the words of a string consisting of multiple words.
Table of contents
Iterate Over Words using istringstream
The simplest way to iterate over words is to use the istringstream class. If the words in a string are separated by whitespace, we can fetch each word from the istringstream object as follows:
#include <iostream>
#include <sstream>
#include <string>
using namespace std;
int main() {
string str = "C++ is really fun to learn!";
istringstream iss(str);
do {
string word;
iss >> word;
cout << word << endl;
} while (iss);
return 0;
}
You can test your code by going to the Online Compiler and Code Executor.
Let’s run the code to get the result:
C++ is really fun to learn!
Iterate Over Words using for loop
We can iterate over the words in a string using iteratively. The steps of this approach are as follows:
#include <iostream>
#include <string>
// Split provided string to words and print to console
void splitWord(std::string str)
{
// Create an empty string
std::string word;
// Iterate over the string character by character with for loop
for (int i = 0; i < str.length(); i++) {
// Check if character at current iteration is equal to ' ' or
// is the last character
if (str[i] == ' ' or i == (str.length() - 1)) {
// If whitespace or the last character print the string including current character
std::cout << word + str[i] << std::endl;
word = "";
}
// Add current character to string
else {
word += str[i];
}
}
}
int main()
{
// Given string
std::string str = "C++ is really fun to learn!";
splitWord(str);
return 0;
}
Let’s run the code to see the result:
C++ is really fun to learn!
Iterate Over Words using strtok
Using the provided separators, we can also use the strtok method to split a string into words. Let’s look at an example using strtok:
#include <cstdio>
#include <cstring>
int main ()
{
// Define a character array
char str[] ="C++ is really fun to learn!";
// Character pointer
char * pch;
printf ("Splitting string \"%s\" into tokens:\n",str);
// Return pointers to the first token
pch = strtok (str," ,.-");
// Check for delimiter
while (pch != nullptr)
{
// Use strtok to go through other tokens
printf ("%s\n",pch);
pch = strtok (nullptr, " ,.-");
}
return 0;
}
C++ is really fun to learn!
Iterate Over Words using Boost Library
We can also use the boost::split method from the Boost library. The split method functions similarly to strtok, where an input sequence is split into tokens given a specific separator. Let’s look at how to implement the split method with an example,
#include <iostream>
#include <string>
#include <boost/algorithm/string.hpp>
int main() {
// Define an input string
std::string input= "C++ is really fun to learn!";
// Define a container to hold copies of references to the substrings
std::vector<std::string> result;
// Split based on tab or white space
boost::split(result, input, boost::is_any_of("\t "));
// Iterate over vector using for loop
int n = result.size();
for (int i = 0; i<n; i++)
// Print words to console
std::cout << result[i] << std::endl;
return 0;
}
Let’s run the code to see the result:
C++ is really fun to learn!
Summary
Congratulations on reading to the end of this tutorial!
For further reading on C++, go to the articles:
Have fun and happy researching!