How can I solve VSCode / g++ not recognising default include files? [duplicate] - c++

Question

This question already has answers here:
Why is "using namespace std;" considered bad practice?
(41 answers)
Closed 9 months ago.
I am very new to coding in C++ and have little to no experience at all. My problem is: I wanted to use strings so i added #include to the includes in my code but VSCode tells me identifier "string" is undefinedC/C++(20). What I have done is added and modified a c_cpp_properties.json file vor VSCode:
{
"configurations": [
{
"name": "Linux",
"includePath": [
"${workspaceFolder}/**",
"/usr/include/**"
],
"defines": [],
"compilerPath": "/usr/bin/gcc",
"cStandard": "gnu17",
"cppStandard": "gnu++14",
"intelliSenseMode": "linux-gcc-x64"
}
],
"version": 4
}
But that didn't solve the problem. Also, I have made sure that C++ is installed, including the g++ compiler. In VSCode I am using following C++ plugins / addons: C/C++ and C/C++ Project Generator (which I don't really use).
This is the relevant part of my code:
#include <iostream>
#include <string>
int main(int argc, char *argv[])
{
string s;
return 0;
}
And this is the error log / debug message:
g++ -std=c++17 -Wall -Wextra -g -Iinc -c src/main.cpp -o src/main.o
src/main.cpp: In function ‘int main(int, char**)’:
src/main.cpp:30:2: error: ‘string’ was not declared in this scope
30 | string s;
| ^~~~~~
src/main.cpp:30:2: note: suggested alternatives:
In file included from /usr/include/c++/9/iosfwd:39,
from /usr/include/c++/9/ios:38,
from /usr/include/c++/9/ostream:38,
from /usr/include/c++/9/iostream:39,
from src/main.cpp:1:
/usr/include/c++/9/bits/stringfwd.h:79:33: note: ‘std::string’
79 | typedef basic_string<char> string;
| ^~~~~~
In file included from /usr/include/c++/9/bits/locale_classes.h:40,
from /usr/include/c++/9/bits/ios_base.h:41,
from /usr/include/c++/9/ios:42,
from /usr/include/c++/9/ostream:38,
from /usr/include/c++/9/iostream:39,
from src/main.cpp:1:
/usr/include/c++/9/string:67:11: note: ‘std::pmr::string’
67 | using string = basic_string<char>;
| ^~~~~~
Solution: Replace string s; with std::string s;.

Answer 1

C++ strings are "hidden" inside the std namespace. The compiler doesn't recognize string because of that.
You could either include the entire std namespace:
using namespace std;
Do this for specifically strings and nothing else:
using std::string;
or type std::string instead of string when initializing strings. The C++ Standard Library is in the compiler's include path by default, you don't need to do anything extra to be able to use its headers.