How to make the input sentence each word reversed in C++?

Question

I am trying to solve this problem.

Write a program that reads one line of text(less than 50 words) and then prints it with each word reversed. For example:

Input: Today is Tuesday
Output: Tuesday is today

And all I'd think of is putting the words in the sentence into an array, and then printing them out from the biggest index to the smallest index. So I write this program, but it won't work. Please help me fix it, thanks so much.

I tried to let it print the words with the index number and I found out that the last "box" of the array stored the whole sentence. But I don't know what's wrong. I don't know where(which line of code) it stored that sentence.

#include <bits/stdc++.h>
using namespace std;

int main(){
    string str;
    cout<<"Put in your sentence: ";
    getline(cin,str);
    string strWords[10];
    int counter = 0;
    for (int i = 0; i<str.length(); i++){
    if (str[i] == ' ')
        counter++;
    else
        strWords[counter] += str[i];
    }

    int j=9;
    do{
        cout<<j<<": "<<strWords[j]<<" ";
        j--;
    }
    while(j>=0);

    return 0;
}

example:

input:

Put in your sentence: WE are the people.

output:

9: WE are the people. 8:  7:  6:  5:  4:  3: people. 2: the 1: are 0: WE

Answer 1

I can not reproduce the problem. However in any case this for loop

int counter = 0;
for (int i = 0; i<str.length(); i++){
if (str[i] == ' ')
    counter++;
else
    strWords[counter] += str[i];
}

is wrong because the user can enter adjacent spaces that can result in using an incorrect index to access the array strwords. And you should preserve the number of spaces between words when the sentence will be outputted.

Just to output a sentence with its words in the reversed order neither array or other container is required. And there is no need to change the original sentence.

You can use for example standard class std::string_view.

Here is a demonstration program.

#include <iostream>
#include <string>
#include <string_view>

int main()
{
    std::string s;

    std::cout << "Put in your sentence: ";

    if ( std::getline( std::cin, s ) && !s.empty() )
    {
        const char *blank = " \t";

        bool skip_blanks = true;

        std::cout << '\"';

        for (std::string_view sv( s ); sv.length() != 0; )
        {
            auto pos = skip_blanks 
                ? sv.find_last_not_of( blank )
                : sv.find_last_of( blank );

            skip_blanks = !skip_blanks;

            pos = pos == std::string_view::npos ? 0 : pos + 1;

            std::cout << sv.substr( pos );

            sv.remove_suffix( sv.length() - pos );
        }

        std::cout << "\"\n";
    }
}

Its output might look like

Put in your sentence: 1 2 3 4 5 6 7 8 9 10
"10 9 8 7 6 5 4 3 2 1"

If actually you want to change the source sentence by reversing its words then you can use standard algorithm std::reverse.

Here is a demonstration program.

#include <iostream>
#include <iomanip>
#include <string>
#include <iterator>
#include <algorithm>

int main()
{
    std::string s;

    std::cout << "Put in your sentence: ";

    if (std::getline( std::cin, s ) && !s.empty())
    {
        const char *blank = " \t";

        for (std::string::size_type last = 0, first = s.find_first_not_of( blank, last );
            first != std::string::npos;
            first = s.find_first_not_of( blank, last ))
        {
            last = s.find_first_of( blank, first );
            if (last == std::string::npos) last = s.size();
            std::reverse( std::next( std::begin( s ), first ), std::next( std::begin( s ), last ) );
        }

        std::reverse( std::begin( s ), std::end( s ) );

        std::cout << std::quoted( s ) << '\n';
    }

Its output might look the same way as shown above for the preceding demonstration program.