stringstream in C++ and its applications

A stringstream associates a string object with a stream allowing you to read from the string as if it were a stream (like cin).

Basic methods are –

clear() — to clear the stream
str() — to get and set string object whose content is present in stream.
operator << — add a string to the stringstream object.
operator >> — read something from the stringstream object,

stringstream class is extremely useful in parsing input.

Applications :

Count number of words in a string

Examples:
Input : Asipu Pawan Kumar
Output : 3

Input : Geeks For Geeks Ide
Output : 4

// CPP program to count words in a string 
// using stringstream. 
#include <bits/stdc++.h> 
using namespace std; 
  
int countWords(string str) 
{ 
    // breaking input into word using string stream 
    stringstream s(str); // Used for breaking words 
    string word; // to store individual words 
  
    int count = 0; 
    while (s >> word) 
        count++; 
    return count; 
} 
  
// Driver code 
int main() 
{ 
    string s = "geeks for geeks geeks "
               "contribution placements"; 
    cout << " Number of words are: " << countWords(s); 
    return 0; 
} 

Output:

  Number of words are: 6

Print frequencies of individual words in a string

Input : Geeks For Geeks Quiz Geeks Quiz Practice Practice
Output : For -> 1
         Geeks -> 3
         Practice -> 2
         Quiz -> 2

Input : Word String Frequency String
Output : Frequency -> 1
         String -> 2
         Word -> 1

// CPP program to demonstrate use of stringstream 
// to count frequencies of words. 
#include <bits/stdc++.h> 
using namespace std; 
  
void printFrequency(string st) 
{ 
    // each word it mapped to it's frequency 
    map<string, int> FW; 
    stringstream ss(st); // Used for breaking words 
    string Word; // To store individual words 
  
    while (ss >> Word) 
        FW[Word]++; 
  
    map<string, int>::iterator m; 
    for (m = FW.begin(); m != FW.end(); m++) 
        cout << m->first << " -> "
             << m->second << "\n"; 
} 
  
// Driver code 
int main() 
{ 
    string s = "Geeks For Geeks Ide"; 
    printFrequency(s); 
    return 0; 
} 

Output:

For -> 1
Geeks -> 2
Ide -> 1

Removing spaces from a string using Stringstream
Converting Strings to Numbers in C/C++

This article is contributed by ASIPU PAWAN KUMAR. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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