splitting a string into an array in C++ without using vector

Question

I am trying to insert a string separated by spaces into an array of strings without using vector in C++. For example:

using namespace std;
int main() {
    string line = "test one two three.";
    string arr[4];

    //codes here to put each word in string line into string array arr
    for(int i = 0; i < 4; i++) {
        cout << arr[i] << endl;
    }
}

I want the output to be:

test
one
two
three.

I know there are already other questions asking string > array in C++, but I could not find any answer satisfying my conditions: splitting a string into an array WITHOUT using vector.

Answer 1

It is possible to turn the string into a stream by using the std::stringstream class (its constructor takes a string as parameter). Once it's built, you can use the >> operator on it (like on regular file based streams), which will extract, or tokenize word from it:

#include <iostream>
#include <sstream>

using namespace std;

int main(){
    string line = "test one two three.";
    string arr[4];
    int i = 0;
    stringstream ssin(line);
    while (ssin.good() && i < 4){
        ssin >> arr[i];
        ++i;
    }
    for(i = 0; i < 4; i++){
        cout << arr[i] << endl;
    }
}

Answer 2

#include <iostream>
#include <sstream>
#include <iterator>
#include <string>

using namespace std;

template <size_t N>
void splitString(string (&arr)[N], string str)
{
    int n = 0;
    istringstream iss(str);
    for (auto it = istream_iterator<string>(iss); it != istream_iterator<string>() && n < N; ++it, ++n)
        arr[n] = *it;
}

int main()
{
    string line = "test one two three.";
    string arr[4];

    splitString(arr, line);

    for (int i = 0; i < 4; i++)
       cout << arr[i] << endl;
}

Answer 3

#define MAXSPACE 25

string line =  "test one two three.";
string arr[MAXSPACE];
string search = " ";
int spacePos;
int currPos = 0;
int k = 0;
int prevPos = 0;

do
{

    spacePos = line.find(search,currPos);

    if(spacePos >= 0)
    {

        currPos = spacePos;
        arr[k] = line.substr(prevPos, currPos - prevPos);
        currPos++;
        prevPos = currPos;
        k++;
    }


}while( spacePos >= 0);

arr[k] = line.substr(prevPos,line.length());

for(int i = 0; i < k; i++)
{
   cout << arr[i] << endl;
}

Answer 4

Here's a suggestion: use two indices into the string, say start and end. start points to the first character of the next string to extract, end points to the character after the last one belonging to the next string to extract. start starts at zero, end gets the position of the first char after start. Then you take the string between [start..end) and add that to your array. You keep going until you hit the end of the string.

Answer 5

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

int main() {

    string s1="split on     whitespace";
    istringstream iss(s1);
    vector<string> result;
    for(string s;iss>>s;)
        result.push_back(s);
    int n=result.size();
    for(int i=0;i<n;i++)
        cout<<result[i]<<endl;
    return 0;
}

Output:-

split
on
whitespace

Answer 6

I made a header for this and you can use it to split a string into array of strings using a string as a splitter heres how:

1. create a file with a name "WordSplitter.h" and save it along with the folder of cpp file.

2. Copy paste this in WordSplitter.h:

#ifndef WORDSPLITTER_H
#undef WORDSPLITTER_H
#include <iostream>
#include <string>
using namespace std;

class Word {
    public:
        string word;
        string list[99];

    Word(string s){
        word = s;
    }
    
    int size(string s){
        int size = 0;
        for(char c : s){
            size ++;
        }
        return size;
    }

    int size(){
        int size = 0;
        for (char c : word){
            size ++;
        }
        return size;
    }

    string slice(int start, int end){
        string result = "";
        for(int i = start ; i <= end ; i ++){
            result += word[i];
        }
        return result;
    }
    
    string sliceThis(string s, int start, int end){
        string result = "";
        for(int i = start ; i <= end ; i ++){
            result += s[i];
        }
        return result;
    }

    int count(string s){
        int count, start = 0;
        for(int end = size(s)-1 ; end < size() ; end ++){
            if(s == slice(start,end)){count ++;}
            start ++;
        }
        return count;
    }
    
    int listSize(){
        int size_ = 0;
        for(string str : list){
            if (size(str) > 0){
                size_ ++;
            }
        }
        return size_;
    }

    void split(string splitter){
        int splitSize = size(splitter) - 1;
        int split_start = 0;
        int split_end, end;
        int index = 0;
        
        if (count(splitter) > 0){
            for(end = splitSize ; end < size() ; end ++){
                int start = end - splitSize;
                if (splitter == slice(start,end)){
                    split_end = start - 1;
                    list[index] = slice(split_start,split_end);
                    split_start = end + 1;
                    end += splitSize;
                    index ++;
                }
            }
            list[index] = slice(split_end + size(splitter) + 1, size());
            //list[index] = slice(end + 1, size());
        }
    }
};

#endif

3. inside your cpp file:

#include <iostream>
#include <string>
#include "WordSplitter.h"

using namespace std;

int main(){ 
    Word mySentence = Word("I[]got[]a[]jar[]of[]dirt");
    mySentence.split("[]"); //use a splitter

    for(int i = 0 ; i < mySentence.count("[]") + 1 ; i ++){
        cout << mySentence.list[i] << endl;
    }

    return 0;
}

output:

I
got
a
jar
of
dirt