Displaying a vector of strings in C

Question

I m sorry if this is a repeat question but I already tried to search for an answer and came  up empty handed  So basically I just want to add strings  single words  to the back of a vector and then display the stored strings as a single string  I am quite the rookie    include  lt iostream gt   include  lt vector gt   include  lt string gt   include  lt cctype gt  using namespace std    int main int a  char  b           vector lt string gt  userString            string word              string sentence                      for  decltype userString size    i   0  i  lt   userString size   - 1  i                  cin  gt  gt  word          userString push back word           sentence    userString i                   cout  lt  lt  sentence      system  PAUSE        return 0      Why doesn t this work   EDIT  int main int a  char  b           cout  lt  lt   Enter a sequence of words  Enter      n       vector lt string gt  userString            string word                          string sentence                       int wordCount   0      while  getline cin  word                 if  word                               break                    userString push back word             for  decltype userString size    i   0  i  lt   userString size   - 1  i                  sentence    userString i                 wordCount    1          if  wordCount    8                        sentence   sentence     n                       wordCount   0                      cout  lt  lt  sentence  lt  lt  endl       system  PAUSE        return 0      So my new program works  It just puts values at the back of a vector and prints them out 8 words to a line  I know there s easier ways but I m just learning vectors and I m going in baby steps  Thanks for the help guys

User · Answer

Because userString is empty  You only declare it  vector lt string gt  userString         but never add anything  so the for loop won t even run

User · Answer

You have to insert the elements using the insert method present in vectors STL  check the below program to add the elements to it  and you can use in the same way in your program    include  lt iostream gt   include  lt vector gt   include  lt string h gt   int main        std  vector lt std  string gt  myvector     std  vector lt std  string gt   iterator it      it   myvector begin      std  string myarray         Hi   hello   wassup       myvector insert  myvector begin    myarray  myarray 3      std  cout  lt  lt   myvector contains      for  it myvector begin    it lt myvector end    it        std  cout  lt  lt       lt  lt   it      std  cout  lt  lt    n      return 0

User · Answer

You ask two questions  your title says  Displaying a vector of strings   but you re not actually doing that  you actually build a single string composed of all the strings and output that   Your question body asks  Why doesn t this work    It doesn t work because your for loop is constrained by  userString size    which is 0  and you test your loop variable for being  userString size   - 1   The condition of a for   loop is tested before permitting execution of the first iteration   int n   1  for  int i   1  i  lt  n    i        std  cout  lt  lt  i  lt  lt  endl      will print exactly nothing   So your loop executes exactly no iterations  leaving userString and sentence empty   Lastly  your code has absolutely zero reason to use a vector  The fact that you used  decltype userString size     instead of  size t  or  auto   while claiming to be a rookie  suggests you re either reading a book from back to front or you are setting yourself up to fail a class   So to answer your question at the end of your post  It doesn t work because you didn t step through it with a debugger and inspect the values as it went  While I say it tongue-in-cheek  I m going to leave it out there

User · Answer

Your vector lt string gt  userString has size 0  so the loop is never entered  You could start with a vector of a given size   vector lt string gt  userString 10         string word          string sentence             for  decltype userString size    i   0  i  lt  userString size      i        cin  gt  gt  word      userString i    word      sentence    userString i             although it is not clear why you need the vector at all   string word          string sentence             for  int i   0  i  lt  10    i        cin  gt  gt  word      sentence    word            If you don t want to have a fixed limit on the number of input words  you can use std  getline in a while loop  checking against a certain input  e g   q    while  std  getline std  cin  word   amp  amp  word     q         sentence    word            This will add words to sentence until you type  q

User · Answer

vector size   returns the size of a vector  You didn t put any string in the vector before the loop   so the size of the vector is 0  It will never enter the loop  First put some data in the vector and then try to add them  You can take input from the user for the number of string user wants to enter    include  lt iostream gt   include  lt vector gt   include  lt string gt   include  lt cctype gt  using namespace std    int main int a  char  b           vector lt string gt  userString      string word      string sentence           int SIZE      cin gt  gt SIZE       what will be the size of the vector     for  int i   0  i  lt  SIZE  i                  cin  gt  gt  word          userString push back word           sentence    userString i                   cout  lt  lt  sentence      system  PAUSE        return 0      another thing  actually you don t have to use a vector to do this Two strings can do the job for you    include  lt iostream gt   include  lt vector gt   include  lt string gt   include  lt cctype gt  using namespace std    int main int a  char  b             vector lt string gt  userString      string word      string sentence           int SIZE      cin gt  gt SIZE       what will be the size of the vector     for  int i   0  i  lt  SIZE  i                  cin  gt  gt  word          sentence    word                 cout  lt  lt  sentence      system  PAUSE        return 0      and if you want to enter string until the user wish   code will be like this    include  lt iostream gt   include  lt vector gt   include  lt string gt   include  lt cctype gt  using namespace std    int main int a  char  b             vector lt string gt  userString      string word      string sentence             int SIZE        cin gt  gt SIZE       what will be the size of the vector     while cin gt  gt word                  cin  gt  gt  word          sentence    word                 cout  lt  lt  sentence        system  PAUSE        return 0

[c++] Displaying a vector of strings in C++

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