How to navigate through a vector using iterators C

Question

The goal is to access the  nth  element of a vector of strings instead of the    operator or the  at  method  From what I understand  iterators can be used to navigate through containers  but I ve never used iterators before  and what I m reading is confusing   If anyone could give me some information on how to achieve this  I would appreciate it  Thank you

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In C  -11 you can do   std  vector lt int gt  v    0  1  2  3  4  5   for  auto i   v          access by value  the type of i is int    std  cout  lt  lt  i  lt  lt         std  cout  lt  lt    n     See here for variations  https   en cppreference com w cpp language range-for

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Vector s iterators are random access iterators which means they look and feel like plain pointers  You can access the nth element by adding n to the iterator returned from the container s begin   method  or you can use operator     std  vector lt int gt  vec 10   std  vector lt int gt   iterator it   vec begin     int sixth     it   5   int third     2   it   int second   it 1    Alternatively you can use the advance function which works with all kinds of iterators   You d have to consider whether you really want to perform  quot random access quot  with non-random-access iterators  since that might be an expensive thing to do   std  vector lt int gt  vec 10   std  vector lt int gt   iterator it   vec begin     std  advance it  5   int sixth    it

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You need to make use of the begin and end method of the vector class  which return the iterator referring to the first and the last element respectively   using namespace std     vector lt string gt  myvector      a vector of stings       push some strings in the vector  myvector push back  a    myvector push back  b    myvector push back  c    myvector push back  d      vector lt string gt   iterator it      declare an iterator to a vector of strings int n   3      nth element to be found  int i   0      counter      now start at from the beginning    and keep iterating over the element till you find    nth element   or reach the end of vector  for it   myvector begin    it    myvector end    it   i                 found nth element  print and break      if i    n            cout lt  lt   it  lt  lt  endl      prints d          break              other easier ways of doing the same     using operator   cout lt  lt myvector n  lt  lt endl      prints d      using the at method cout  lt  lt  myvector at n   lt  lt  endl      prints d

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Here is an example of accessing the ith index of a std  vector using an std  iterator within a loop which does not require incrementing two iterators   std  vector lt std  string gt  strs     sigma   alpha    beta    rho    nova    int nth   2  std  vector lt std  string gt   iterator it  for it   strs begin    it    strs end    it          int ith   it - strs begin        if ith    nth            printf  Iterator within  a for-loop  strs  d     s n   ith    it  c str               Without a for-loop  it   strs begin     nth  printf  Iterator without a for-loop  strs  d     s n   nth    it  c str       and using at method       printf  Using at position  strs  d     s n   nth  strs at nth  c str

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Typically  iterators are used to access elements of a container in linear fashion  however  with  random access iterators   it is possible to access any element in the same fashion as operator      To access arbitrary elements in a vector vec  you can use the following   vec begin                       1st vec begin   1                   2nd        vec begin    i-1                ith        vec begin    vec size  -1       last   The following is an example of a typical access pattern  earlier versions of C      int sum   0  using Iter   std  vector lt int gt   const iterator  for  Iter it   vec begin    it  vec end      it        sum     it      The advantage of using iterator is that you can apply the same pattern with other containers   sum   0  for  Iter it   lst begin    it  lst end      it        sum     it      For this reason  it is really easy to create template code that will work the same regardless of the container type  Another advantage of iterators is that it doesn t assume the data is resident in memory  for example  one could create a forward iterator that can read data from an input stream  or that simply generates data on the fly  e g  a range or random number generator    Another option using std  for each and lambdas   sum   0  std  for each vec begin    vec end      amp sum  int i    sum    i        Since C  11 you can use auto to avoid specifying a very long  complicated type name of the iterator as seen before  or even more complex     sum   0  for  auto it   vec begin    it  vec end      it        sum     it      And  in addition  there is a simpler for-each variant   sum   0  for  auto value   vec        sum    value      And finally there is also std  accumulate where you have to be careful whether you are adding integer or floating point numbers

[c++] How to navigate through a vector using iterators? (C++)

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