CODEWITHSUNDEEP
c++stringparsingsubstring
hmz
hmz

Reputation: 1017

i want to take out words from a string sentence and get this error in c++

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

void extractFirstWord(string& sentence, string& word);
void processBlanks(string& sentence);

int main() {
    string sentence, word;
    cout << "Input a sentence: ";
    getline(cin, sentence);

    while (sentence != "") {
          processBlanks(sentence); // removes all blanks from the front of sentence
          if (sentence.length() > 0) { // removing blanks may have made sentence null - cannot extract from a null string
             extractFirstWord(sentence, word); // gets first word from sentence and puts into word
             cout << word << endl; // output one word at a time
          }
    }

    system("PAUSE");
    return 0;
}

void extractFirstWord(string& sentence, string& word)
    {
        int i=0;
        while(sentence[i]!=' ')
        {
            i++;        
        }
        word=sentence.substr(0,i);
        sentence=sentence.substr(i);
}
// extractFirstWord removes the substring of sentence 
// from the beginning to the first space from sentence 
// and stores the same string into word. sentence is
// shortened accordingly.
// Postcondition: sentence is shortened, and word
//                is appropriately the first word in
//                sentence.

void processBlanks(string& sentence)
    {
        int i=0;
        while(sentence[i]==' '){i++;}
        sentence=sentence.substr(i);
    }

processBlanks will remove all of the spaces in front of sentence. Postcondition: sentence has no spaces in front of the first word.

i want to take out words from a string sentence and get this error in c++

Error is -> String subscript out of range

Upvotes: 0

Views: 2137

Answers (4)

Arun
Arun

Reputation: 2092

void extractFirstWord(string& sentence, string& word)
{
    int i=0;
    while(i<sentence.size() && sentence[i]!=' ')  // i should be less than sentence size
    {
        i++;        
    }
    word=sentence.substr(0,i);
    sentence=sentence.substr(i);

}

Upvotes: 0

BLUEPIXY
BLUEPIXY

Reputation: 40145

use stringstream

#include <iostream>
#include <sstream>

int main(){
    std::stringstream ss("   first second.   ");

    std::string word;

    ss >> word;

    std::cout << word << std::endl;//first
}

Upvotes: 0

Onur A.
Onur A.

Reputation: 3017

just consider the case when the input has no spaces, your variable i will increment till length of word and in that case it will be out of range. try to check whether i equals to length of word before the substr() method

Upvotes: 0

Joseph Mansfield
Joseph Mansfield

Reputation: 110658

In extractFirstWord, you keep increasing i if you haven't yet found a space. However, you might index past the end of the string if it's the last word in the string. Change the while condition like so:

while(i < sentence.length() && sentence[i]!=' ')

Upvotes: 3

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