Using push_back on a vector of strings - C++

Question

I am trying to use push_back on a vector of strings in C++. How can I push a single character on to the vector? Currently, I have tried the following, all without success:

Initialized a string (tried to) with the character.

Code

string str(main_string[0]);  
vector_string.push_back(str);

Tried to invoke strcpy and thus copy contents. Const-ness seems to get in the way.

Code

string str;  
strcpy(main_string[0], str.c_str());  
vector_string.push_back(str);

Any more suggestions/ideas are most welcome.

Edit: The error logs are as follows:

test_push.C: In function ‘void test_push(std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&, std::string)’:
test_push.C:50: error: no matching function for call to ‘std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(char&)’
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/basic_string.tcc:220: note: candidates are: std::basic_string<_CharT, _Traits, _Alloc>::basic_string(typename _Alloc::rebind<_CharT>::other::size_type, _CharT, const _Alloc&) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/basic_string.tcc:213: note:                 std::basic_string<_CharT, _Traits, _Alloc>::basic_string(const _CharT*, const _Alloc&) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>] <near match>
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/basic_string.tcc:206: note:                 std::basic_string<_CharT, _Traits, _Alloc>::basic_string(const _CharT*, typename _Alloc::rebind<_CharT>::other::size_type, const _Alloc&) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/basic_string.tcc:194: note:                 std::basic_string<_CharT, _Traits, _Alloc>::basic_string(const std::basic_string<_CharT, _Traits, _Alloc>&, typename _Alloc::rebind<_CharT>::other::size_type, typename _Alloc::rebind<_CharT>::other::size_type, const _Alloc&) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/basic_string.tcc:184: note:                 std::basic_string<_CharT, _Traits, _Alloc>::basic_string(const std::basic_string<_CharT, _Traits, _Alloc>&, typename _Alloc::rebind<_CharT>::other::size_type, typename _Alloc::rebind<_CharT>::other::size_type) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/basic_string.tcc:170: note:                 std::basic_string<_CharT, _Traits, _Alloc>::basic_string(const std::basic_string<_CharT, _Traits, _Alloc>&) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/basic_string.tcc:178: note:                 std::basic_string<_CharT, _Traits, _Alloc>::basic_string(const _Alloc&) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/basic_string.h:2147: note:                 std::basic_string<_CharT, _Traits, _Alloc>::basic_string() [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]
test_push.C:61: error: conversion from ‘char’ to non-scalar type ‘std::string’ requested
test_push:90: error: no matching function for call to ‘std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(char&)’
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/basic_string.tcc:220: note: candidates are: std::basic_string<_CharT, _Traits, _Alloc>::basic_string(typename _Alloc::rebind<_CharT>::other::size_type, _CharT, const _Alloc&) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/basic_string.tcc:213: note:                 std::basic_string<_CharT, _Traits, _Alloc>::basic_string(const _CharT*, const _Alloc&) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>] <near match>
/usr/lib/gcc/i586-redhat-linux/4.4.1/../../../../include/c++/4.4.1/bits/basic_string.tcc:206: note:                 std::basic_string<_CharT, _Traits, _Alloc>::basic_string(const _CharT*, typename _Alloc::rebind<_CharT>::other::size_type, const _Alloc&) [with _CharT = char, _Traits = std::char_traits<char>, _Alloc = std::allocator<char>]

More info: In this function, either the entire string or just the first letter is pushed in to the vector based on its contents. So, in a way, I am looking for some function that converts a char into a C++ style std::string (to make it acceptable to a vector).

Thanks,
Sriram

What are the errors you are actually getting? Also, in the second one, are you trying to copy str into main_string[0] or vice versa? — flight
– flight, Commented Mar 16, 2011 at 8:16
string is in turn a vector of characters. Why do you want to create a vector with string ( but only one character)? — aJ.
– aJ., Commented Mar 16, 2011 at 8:18
Actually your problem is, initializing a string with one character. — ali_bahoo
– ali_bahoo, Commented Mar 16, 2011 at 8:20

ali_bahoo · Accepted Answer · 2011-03-16 08:25:50Z

8

You can also initialize with one character like this.

string str(1,main_string[0]);  
vector_string.push_back(str);

answered Mar 16, 2011 at 8:25

ali_bahoo

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Community · Accepted Answer · 2017-05-23 11:53:08Z

6

You can add the character directly via an appropriate string constructor:

vector_string.push_back(string(1, main_string[0]));

EDIT: Removed alternate solution after realising it duplicates @Tim's.

edited May 23, 2017 at 11:53

CommunityBot

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answered Mar 16, 2011 at 8:27

Marcelo Cantos

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Tim · Accepted Answer · 2011-03-16 08:20:38Z

5

no need for strcpy for a single character.

string str ("x");
str[0] = main_string[0]; 
vector_string.push_back(str);

answered Mar 16, 2011 at 8:20

Tim

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2 Comments

user168715 Over a year ago

Or even just string str; str += main_string[0];.

Tim Over a year ago

or string str (main_string, 0, 1); There's a lot of ways to do this!

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