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 :

1. 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; }

   Run on IDE

   Output:

     Number of words are: 6

2. 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; }

   Run on IDE

   Output:

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

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

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