CODEWITHSUNDEEP
c++vector
mittal_sahil
mittal_sahil

Reputation: 33

error:- main.cpp:11:19: error: no matching function for call in the push_back line

I have been trying to execute this code, and I am getting an error:

main.cpp:11:19: error: no matching function for call to ‘std::vector<std::__cxx11::basic_string<char> >::push_back(__gnu_cxx::__alloc_traits<std::allocator<char> >::value_type&)’
   v.push_back(s[2]);

#include <iostream>
#include<vector>

using namespace std;

int main()
{
    string s;
    s="abc";
    vector<string>v;
    v.push_back(s[2]);
    cout<<v[0];
   
    return 0;
}

Upvotes: 0

Views: 944

Answers (3)

Remy Lebeau
Remy Lebeau

Reputation: 595672

You are trying to push a single char into a std::vector of std::string elements. std::string does not have a constructor that takes only a single char as input (but it does have an operator= that does).

So, you will have to either:

  • Change the std::vector to hold char elements instead of std::string elements:
#include <iostream>
#include <vector>
#include <string>

using namespace std;

int main()
{
    string s = "abc";
    vector<char> v;
    v.push_back(s[2]);
    cout << v[0];
   
    return 0;
}
  • Change how you are constructing the std::string objects that you are pushing into the std::vector:
#include <iostream>
#include <vector>
#include <string>

using namespace std;

int main()
{
    string s = "abc";
    vector<string> v;

    v.push_back(string(1, s[2]));
    //
    // or:
    // v.push_back(string(&s[2], 1));
    //
    // or:
    // string tmp;
    // tmp = s[2];
    // v.push_back(tmp);

    cout << v[0];
   
    return 0;
}

Upvotes: 0

MikeCAT
MikeCAT

Reputation: 75062

s[2] is a character (type char), so it cannot be inserted to vectors that accept string.

The constructor of std::string

basic_string( size_type count,
              CharT ch,
              const Allocator& alloc = Allocator() );

is useful to create strings from one character.

Try this:

#include <iostream>
#include<vector>

using namespace std;

int main()
{
    string s;
    s="abc";
    vector<string>v;
    v.push_back(std::string(1, s[2]));
    cout<<v[0];

    return 0;
}

Upvotes: 1

cigien
cigien

Reputation: 60208

Indexing into a string like this:

s[2]

gives you a char, and there's no overload of push_back for vector<string> that takes a char.

Instead, you can use the initializer list constructor for string like this, to pass a string containing a single character:

v.push_back( { s[2] } );

Upvotes: 1

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