Trying push a string backwards into a vector

-1

#include <iostream>

#include <vector>

#include <string>

#include <stdio.h>

#include <stdlib.h>

using namespace std;



class thing{

public:

    vector<unsigned short> vec;

    thing(string);

};



int main(){

    thing adam("12345");

    for(int i = adam.vec.size() - 1;i >= 0;i--){

        cout << adam.vec[i] << endl;

    }

}



thing::thing(string str){

    for(int i = str.size() - 1; i >= 0;i--){

        cout << str[i] << endl;

        vec.push_back(str[i]);

    }

}

I'm trying to make a constructor that takes in a string and fills the vector with the string in reverse, but instead of filling the vector with the values 5,4,3,2,1, it fills it with 53,52,51,59,49. This happens when I call push_back() and I'm confused on why.

edited Nov 12 '18 at 23:22

Remy Lebeau

333k18251446

asked Nov 12 '18 at 22:21

Adam Jean-Laurent

4

Hint: std::string::rbegin is a thing. As is constructing a string from a pair of (reverse) iterators. You are writing way more code than you need to in order to solve rhis.

– Jesper Juhl
Nov 12 '18 at 22:25

3

This has nothing to do with strings or vectors. You'd get the same results by doing unsigned short n = '5'; cout << n << "n";.

– melpomene
Nov 12 '18 at 22:28

add a comment |

-1

#include <iostream>

#include <vector>

#include <string>

#include <stdio.h>

#include <stdlib.h>

using namespace std;



class thing{

public:

    vector<unsigned short> vec;

    thing(string);

};



int main(){

    thing adam("12345");

    for(int i = adam.vec.size() - 1;i >= 0;i--){

        cout << adam.vec[i] << endl;

    }

}



thing::thing(string str){

    for(int i = str.size() - 1; i >= 0;i--){

        cout << str[i] << endl;

        vec.push_back(str[i]);

    }

}

edited Nov 12 '18 at 23:22

Remy Lebeau

333k18251446

asked Nov 12 '18 at 22:21

Adam Jean-Laurent

4

Hint: std::string::rbegin is a thing. As is constructing a string from a pair of (reverse) iterators. You are writing way more code than you need to in order to solve rhis.

– Jesper Juhl
Nov 12 '18 at 22:25

3

This has nothing to do with strings or vectors. You'd get the same results by doing unsigned short n = '5'; cout << n << "n";.

– melpomene
Nov 12 '18 at 22:28

add a comment |

-1

#include <iostream>

#include <vector>

#include <string>

#include <stdio.h>

#include <stdlib.h>

using namespace std;



class thing{

public:

    vector<unsigned short> vec;

    thing(string);

};



int main(){

    thing adam("12345");

    for(int i = adam.vec.size() - 1;i >= 0;i--){

        cout << adam.vec[i] << endl;

    }

}



thing::thing(string str){

    for(int i = str.size() - 1; i >= 0;i--){

        cout << str[i] << endl;

        vec.push_back(str[i]);

    }

}

edited Nov 12 '18 at 23:22

Remy Lebeau

333k18251446

asked Nov 12 '18 at 22:21

Adam Jean-Laurent

#include <iostream>

#include <vector>

#include <string>

#include <stdio.h>

#include <stdlib.h>

using namespace std;



class thing{

public:

    vector<unsigned short> vec;

    thing(string);

};



int main(){

    thing adam("12345");

    for(int i = adam.vec.size() - 1;i >= 0;i--){

        cout << adam.vec[i] << endl;

    }

}



thing::thing(string str){

    for(int i = str.size() - 1; i >= 0;i--){

        cout << str[i] << endl;

        vec.push_back(str[i]);

    }

}

c++

edited Nov 12 '18 at 23:22

Remy Lebeau

333k18251446

asked Nov 12 '18 at 22:21

Adam Jean-Laurent

edited Nov 12 '18 at 23:22

Remy Lebeau

333k18251446

asked Nov 12 '18 at 22:21

Adam Jean-Laurent

edited Nov 12 '18 at 23:22

Remy Lebeau

333k18251446

edited Nov 12 '18 at 23:22

Remy Lebeau

333k18251446

edited Nov 12 '18 at 23:22

Remy Lebeau

333k18251446

asked Nov 12 '18 at 22:21

Adam Jean-Laurent

asked Nov 12 '18 at 22:21

Adam Jean-Laurent

asked Nov 12 '18 at 22:21

Adam Jean-Laurent

4

Hint: std::string::rbegin is a thing. As is constructing a string from a pair of (reverse) iterators. You are writing way more code than you need to in order to solve rhis.

– Jesper Juhl
Nov 12 '18 at 22:25

3

This has nothing to do with strings or vectors. You'd get the same results by doing unsigned short n = '5'; cout << n << "n";.

– melpomene
Nov 12 '18 at 22:28

add a comment |

4

Hint: std::string::rbegin is a thing. As is constructing a string from a pair of (reverse) iterators. You are writing way more code than you need to in order to solve rhis.

– Jesper Juhl
Nov 12 '18 at 22:25

3

This has nothing to do with strings or vectors. You'd get the same results by doing unsigned short n = '5'; cout << n << "n";.

– melpomene
Nov 12 '18 at 22:28

Hint: std::string::rbegin is a thing. As is constructing a string from a pair of (reverse) iterators. You are writing way more code than you need to in order to solve rhis.

– Jesper Juhl
Nov 12 '18 at 22:25

This has nothing to do with strings or vectors. You'd get the same results by doing unsigned short n = '5'; cout << n << "n";.

– melpomene
Nov 12 '18 at 22:28

add a comment |

2 Answers
2

active

oldest

votes

I'm trying to make a constructor that takes in a string and fills the vector with the string in reverse

You probably don't really want to do that. As @JesperJuhl suggests - you can always just access the string in reverse. Why the needless copy?

instead of filling the vector with the values 5,4,3,2,1, it fills it with 53,52,51,59,49

You're mistaking the characters '5', '4', '3' with their integer values. The values of string elements are numbers, but those numbers are indices into some character set. Without going into too much detail about - here's the relevant fragment of the character set in your case:

enter image description here

Indeed, the character '5' has index 53 (decimal) within the character set, '4' has 52 and so on.

answered Nov 12 '18 at 22:37

einpoklum

33.9k27122241

1

We could do without another image of the ASCII table.

– n.m.
Nov 12 '18 at 22:43

@n.m.: To be honest, this question is rather redundant. If you find a good dupe, I promise to remove my entire answer, not just the table...

– einpoklum
Nov 12 '18 at 22:54

I couldn't find a dupe though I know there are some.

– n.m.
Nov 12 '18 at 22:58

add a comment |

for(int i = adam.vec.size() - 1;i >= 0;i--)

    cout << adam.vec[i] << endl;

Your code to insert in reverse order is working just fine. But you are displaying the vector in reverse order also, so it goes back to previous order. To display in correct order, just use:

thing adam("12345");

for(size_t i = 0; i < adam.vec.size(); i++)

    cout << adam.vec[i] << ' ';

cout << endl;

//or 

for(const auto &element : adam.vec)

    cout << element << ' ';

cout << endl;

Your method for(int i = str.size() - 1; i >= 0;i--){...} for iterating backward works in most cases, but casting size in to int can be a problem. The standard library offers other methods. Example:

thing::thing(string str) 

{

    std::copy(str.crbegin(), str.crend(), std::back_inserter(vec));

}

Or use iterators to traverse forward or backward.

answered Nov 13 '18 at 5:24

Barmak Shemirani

21.1k42145

add a comment |

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

I'm trying to make a constructor that takes in a string and fills the vector with the string in reverse

You probably don't really want to do that. As @JesperJuhl suggests - you can always just access the string in reverse. Why the needless copy?

instead of filling the vector with the values 5,4,3,2,1, it fills it with 53,52,51,59,49

enter image description here

Indeed, the character '5' has index 53 (decimal) within the character set, '4' has 52 and so on.

answered Nov 12 '18 at 22:37

einpoklum

33.9k27122241

1

We could do without another image of the ASCII table.

– n.m.
Nov 12 '18 at 22:43

@n.m.: To be honest, this question is rather redundant. If you find a good dupe, I promise to remove my entire answer, not just the table...

– einpoklum
Nov 12 '18 at 22:54

I couldn't find a dupe though I know there are some.

– n.m.
Nov 12 '18 at 22:58

add a comment |

I'm trying to make a constructor that takes in a string and fills the vector with the string in reverse

You probably don't really want to do that. As @JesperJuhl suggests - you can always just access the string in reverse. Why the needless copy?

instead of filling the vector with the values 5,4,3,2,1, it fills it with 53,52,51,59,49

enter image description here

Indeed, the character '5' has index 53 (decimal) within the character set, '4' has 52 and so on.

answered Nov 12 '18 at 22:37

einpoklum

33.9k27122241

1

We could do without another image of the ASCII table.

– n.m.
Nov 12 '18 at 22:43

@n.m.: To be honest, this question is rather redundant. If you find a good dupe, I promise to remove my entire answer, not just the table...

– einpoklum
Nov 12 '18 at 22:54

I couldn't find a dupe though I know there are some.

– n.m.
Nov 12 '18 at 22:58

add a comment |

I'm trying to make a constructor that takes in a string and fills the vector with the string in reverse

You probably don't really want to do that. As @JesperJuhl suggests - you can always just access the string in reverse. Why the needless copy?

instead of filling the vector with the values 5,4,3,2,1, it fills it with 53,52,51,59,49

enter image description here

Indeed, the character '5' has index 53 (decimal) within the character set, '4' has 52 and so on.

answered Nov 12 '18 at 22:37

einpoklum

33.9k27122241

I'm trying to make a constructor that takes in a string and fills the vector with the string in reverse

You probably don't really want to do that. As @JesperJuhl suggests - you can always just access the string in reverse. Why the needless copy?

instead of filling the vector with the values 5,4,3,2,1, it fills it with 53,52,51,59,49

enter image description here

Indeed, the character '5' has index 53 (decimal) within the character set, '4' has 52 and so on.

answered Nov 12 '18 at 22:37

einpoklum

33.9k27122241

answered Nov 12 '18 at 22:37

einpoklum

33.9k27122241

answered Nov 12 '18 at 22:37

einpoklum

33.9k27122241

answered Nov 12 '18 at 22:37

einpoklum

33.9k27122241

1

We could do without another image of the ASCII table.

– n.m.
Nov 12 '18 at 22:43

@n.m.: To be honest, this question is rather redundant. If you find a good dupe, I promise to remove my entire answer, not just the table...

– einpoklum
Nov 12 '18 at 22:54

I couldn't find a dupe though I know there are some.

– n.m.
Nov 12 '18 at 22:58

add a comment |

1

We could do without another image of the ASCII table.

– n.m.
Nov 12 '18 at 22:43

@n.m.: To be honest, this question is rather redundant. If you find a good dupe, I promise to remove my entire answer, not just the table...

– einpoklum
Nov 12 '18 at 22:54

I couldn't find a dupe though I know there are some.

– n.m.
Nov 12 '18 at 22:58

We could do without another image of the ASCII table.

– n.m.
Nov 12 '18 at 22:43

@n.m.: To be honest, this question is rather redundant. If you find a good dupe, I promise to remove my entire answer, not just the table...

– einpoklum
Nov 12 '18 at 22:54

I couldn't find a dupe though I know there are some.

– n.m.
Nov 12 '18 at 22:58

add a comment |

for(int i = adam.vec.size() - 1;i >= 0;i--)

    cout << adam.vec[i] << endl;

Your code to insert in reverse order is working just fine. But you are displaying the vector in reverse order also, so it goes back to previous order. To display in correct order, just use:

thing adam("12345");

for(size_t i = 0; i < adam.vec.size(); i++)

    cout << adam.vec[i] << ' ';

cout << endl;

//or 

for(const auto &element : adam.vec)

    cout << element << ' ';

cout << endl;

thing::thing(string str) 

{

    std::copy(str.crbegin(), str.crend(), std::back_inserter(vec));

}

Or use iterators to traverse forward or backward.

answered Nov 13 '18 at 5:24

Barmak Shemirani

21.1k42145

add a comment |

for(int i = adam.vec.size() - 1;i >= 0;i--)

    cout << adam.vec[i] << endl;

Your code to insert in reverse order is working just fine. But you are displaying the vector in reverse order also, so it goes back to previous order. To display in correct order, just use:

thing adam("12345");

for(size_t i = 0; i < adam.vec.size(); i++)

    cout << adam.vec[i] << ' ';

cout << endl;

//or 

for(const auto &element : adam.vec)

    cout << element << ' ';

cout << endl;

thing::thing(string str) 

{

    std::copy(str.crbegin(), str.crend(), std::back_inserter(vec));

}

Or use iterators to traverse forward or backward.

answered Nov 13 '18 at 5:24

Barmak Shemirani

21.1k42145

add a comment |

for(int i = adam.vec.size() - 1;i >= 0;i--)

    cout << adam.vec[i] << endl;

Your code to insert in reverse order is working just fine. But you are displaying the vector in reverse order also, so it goes back to previous order. To display in correct order, just use:

thing adam("12345");

for(size_t i = 0; i < adam.vec.size(); i++)

    cout << adam.vec[i] << ' ';

cout << endl;

//or 

for(const auto &element : adam.vec)

    cout << element << ' ';

cout << endl;

thing::thing(string str) 

{

    std::copy(str.crbegin(), str.crend(), std::back_inserter(vec));

}

Or use iterators to traverse forward or backward.

answered Nov 13 '18 at 5:24

Barmak Shemirani

21.1k42145

for(int i = adam.vec.size() - 1;i >= 0;i--)

    cout << adam.vec[i] << endl;

Your code to insert in reverse order is working just fine. But you are displaying the vector in reverse order also, so it goes back to previous order. To display in correct order, just use:

thing adam("12345");

for(size_t i = 0; i < adam.vec.size(); i++)

    cout << adam.vec[i] << ' ';

cout << endl;

//or 

for(const auto &element : adam.vec)

    cout << element << ' ';

cout << endl;

thing::thing(string str) 

{

    std::copy(str.crbegin(), str.crend(), std::back_inserter(vec));

}

Or use iterators to traverse forward or backward.

answered Nov 13 '18 at 5:24

Barmak Shemirani

21.1k42145

answered Nov 13 '18 at 5:24

Barmak Shemirani

21.1k42145

answered Nov 13 '18 at 5:24

Barmak Shemirani

21.1k42145

answered Nov 13 '18 at 5:24

Barmak Shemirani

21.1k42145

add a comment |

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