int main(void)
{
std::cout < "Hello world!" < std:endl;
}
~~~
You get this error message:
~~~
a.cc: In function ‘int main()’:
a.cc:5:13: error: no match for ‘operator<’ (operand types are ‘std::ostream’ {aka ‘std::basic_ostream’} and ‘const char [13]’)
5 | std::cout < "Hello world!" < std:endl;
| ~~~~~~~~~ ^ ~~~~~~~~~~~~~~
| | |
| | const char [13]
| std::ostream {aka std::basic_ostream}
In file included from /usr/local/include/c++/10.0.1/bits/stl_algobase.h:64,
from /usr/local/include/c++/10.0.1/bits/char_traits.h:39,
from /usr/local/include/c++/10.0.1/ios:40,
from /usr/local/include/c++/10.0.1/ostream:38,
from /usr/local/include/c++/10.0.1/iostream:39,
from a.cc:1:
/usr/local/include/c++/10.0.1/bits/stl_pair.h:489:5: note: candidate: ‘template constexpr bool std::operator<(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)’
489 | operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
| ^~~~~~~~
/usr/local/include/c++/10.0.1/bits/stl_pair.h:489:5: note: template argument deduction/substitution failed:
a.cc:5:15: note: ‘std::ostream’ {aka ‘std::basic_ostream’} is not derived from ‘const std::pair<_T1, _T2>’
5 | std::cout < "Hello world!" < std:endl;
| ^~~~~~~~~~~~~~
In file included from /usr/local/include/c++/10.0.1/bits/stl_algobase.h:67,
from /usr/local/include/c++/10.0.1/bits/char_traits.h:39,
from /usr/local/include/c++/10.0.1/ios:40,
from /usr/local/include/c++/10.0.1/ostream:38,
from /usr/local/include/c++/10.0.1/iostream:39,
from a.cc:1:
/usr/local/include/c++/10.0.1/bits/stl_iterator.h:366:5: note: candidate: ‘template bool std::operator<(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&)’
366 | operator<(const reverse_iterator<_Iterator>& __x,
| ^~~~~~~~
/usr/local/include/c++/10.0.1/bits/stl_iterator.h:366:5: note: template argument deduction/substitution failed:
a.cc:5:15: note: ‘std::ostream’ {aka ‘std::basic_ostream’} is not derived from ‘const std::reverse_iterator<_Iterator>’
5 | std::cout < "Hello world!" < std:endl;
| ^~~~~~~~~~~~~~
In file included from /usr/local/include/c++/10.0.1/bits/stl_algobase.h:67,
from /usr/local/include/c++/10.0.1/bits/char_traits.h:39,
from /usr/local/include/c++/10.0.1/ios:40,
from /usr/local/include/c++/10.0.1/ostream:38,
from /usr/local/include/c++/10.0.1/iostream:39,
from a.cc:1:
/usr/local/include/c++/10.0.1/bits/stl_iterator.h:404:5: note: candidate: ‘template bool std::operator<(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_IteratorR>&)’
404 | operator<(const reverse_iterator<_IteratorL>& __x,
| ^~~~~~~~
/usr/local/include/c++/10.0.1/bits/stl_iterator.h:404:5: note: template argument deduction/substitution failed:
a.cc:5:15: note: ‘std::ostream’ {aka ‘std::basic_ostream’} is not derived from ‘const std::reverse_iterator<_Iterator>’
5 | std::cout < "Hello world!" < std:endl;
| ^~~~~~~~~~~~~~
In file included from /usr/local/include/c++/10.0.1/bits/stl_algobase.h:67,
from /usr/local/include/c++/10.0.1/bits/char_traits.h:39,
from /usr/local/include/c++/10.0.1/ios:40,
from /usr/local/include/c++/10.0.1/ostream:38,
from /usr/local/include/c++/10.0.1/iostream:39,
from a.cc:1:
/usr/local/include/c++/10.0.1/bits/stl_iterator.h:1451:5: note: candidate: ‘template bool std::operator<(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorR>&)’
1451 | operator<(const move_iterator<_IteratorL>& __x,
| ^~~~~~~~
/usr/local/include/c++/10.0.1/bits/stl_iterator.h:1451:5: note: template argument deduction/substitution failed:
a.cc:5:15: note: ‘std::ostream’ {aka ‘std::basic_ostream’} is not derived from ‘const std::move_iterator<_IteratorL>’
5 | std::cout < "Hello world!" < std:endl;
| ^~~~~~~~~~~~~~
In file included from /usr/local/include/c++/10.0.1/bits/stl_algobase.h:67,
from /usr/local/include/c++/10.0.1/bits/char_traits.h:39,
from /usr/local/include/c++/10.0.1/ios:40,
from /usr/local/include/c++/10.0.1/ostream:38,
from /usr/local/include/c++/10.0.1/iostream:39,
from a.cc:1:
/usr/local/include/c++/10.0.1/bits/stl_iterator.h:1507:5: note: candidate: ‘template bool std::operator<(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorL>&)’
1507 | operator<(const move_iterator<_Iterator>& __x,
| ^~~~~~~~
/usr/local/include/c++/10.0.1/bits/stl_iterator.h:1507:5: note: template argument deduction/substitution failed:
a.cc:5:15: note: ‘std::ostream’ {aka ‘std::basic_ostream’} is not derived from ‘const std::move_iterator<_IteratorL>’
5 | std::cout < "Hello world!" < std:endl;
| ^~~~~~~~~~~~~~
In file included from /usr/local/include/c++/10.0.1/string:55,
from /usr/local/include/c++/10.0.1/bits/locale_classes.h:40,
from /usr/local/include/c++/10.0.1/bits/ios_base.h:41,
from /usr/local/include/c++/10.0.1/ios:42,
from /usr/local/include/c++/10.0.1/ostream:38,
from /usr/local/include/c++/10.0.1/iostream:39,
from a.cc:1:
/usr/local/include/c++/10.0.1/bits/basic_string.h:6267:5: note: candidate: ‘template bool std::operator<(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&)’
6267 | operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
| ^~~~~~~~
/usr/local/include/c++/10.0.1/bits/basic_string.h:6267:5: note: template argument deduction/substitution failed:
a.cc:5:15: note: ‘std::ostream’ {aka ‘std::basic_ostream’} is not derived from ‘const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>’
5 | std::cout < "Hello world!" < std:endl;
| ^~~~~~~~~~~~~~
In file included from /usr/local/include/c++/10.0.1/string:55,
from /usr/local/include/c++/10.0.1/bits/locale_classes.h:40,
from /usr/local/include/c++/10.0.1/bits/ios_base.h:41,
from /usr/local/include/c++/10.0.1/ios:42,
from /usr/local/include/c++/10.0.1/ostream:38,
from /usr/local/include/c++/10.0.1/iostream:39,
from a.cc:1:
/usr/local/include/c++/10.0.1/bits/basic_string.h:6280:5: note: candidate: ‘template bool std::operator<(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&, const _CharT*)’
6280 | operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
| ^~~~~~~~
/usr/local/include/c++/10.0.1/bits/basic_string.h:6280:5: note: template argument deduction/substitution failed:
a.cc:5:15: note: ‘std::ostream’ {aka ‘std::basic_ostream’} is not derived from ‘const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>’
5 | std::cout < "Hello world!" < std:endl;
| ^~~~~~~~~~~~~~
In file included from /usr/local/include/c++/10.0.1/string:55,
from /usr/local/include/c++/10.0.1/bits/locale_classes.h:40,
from /usr/local/include/c++/10.0.1/bits/ios_base.h:41,
from /usr/local/include/c++/10.0.1/ios:42,
from /usr/local/include/c++/10.0.1/ostream:38,
from /usr/local/include/c++/10.0.1/iostream:39,
from a.cc:1:
/usr/local/include/c++/10.0.1/bits/basic_string.h:6292:5: note: candidate: ‘template bool std::operator<(const _CharT*, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&)’
6292 | operator<(const _CharT* __lhs,
| ^~~~~~~~
/usr/local/include/c++/10.0.1/bits/basic_string.h:6292:5: note: template argument deduction/substitution failed:
a.cc:5:15: note: mismatched types ‘const _CharT*’ and ‘std::basic_ostream’
5 | std::cout < "Hello world!" < std:endl;
| ^~~~~~~~~~~~~~
In file included from /usr/local/include/c++/10.0.1/bits/ios_base.h:46,
from /usr/local/include/c++/10.0.1/ios:42,
from /usr/local/include/c++/10.0.1/ostream:38,
from /usr/local/include/c++/10.0.1/iostream:39,
from a.cc:1:
/usr/local/include/c++/10.0.1/system_error:252:3: note: candidate: ‘bool std::operator<(const std::error_code&, const std::error_code&)’
252 | operator<(const error_code& __lhs, const error_code& __rhs) noexcept
| ^~~~~~~~
/usr/local/include/c++/10.0.1/system_error:252:31: note: no known conversion for argument 1 from ‘std::ostream’ {aka ‘std::basic_ostream’} to ‘const std::error_code&’
252 | operator<(const error_code& __lhs, const error_code& __rhs) noexcept
| ~~~~~~~~~~~~~~~~~~^~~~~
/usr/local/include/c++/10.0.1/system_error:379:3: note: candidate: ‘bool std::operator<(const std::error_condition&, const std::error_condition&)’
379 | operator<(const error_condition& __lhs,
| ^~~~~~~~
/usr/local/include/c++/10.0.1/system_error:379:36: note: no known conversion for argument 1 from ‘std::ostream’ {aka ‘std::basic_ostream’} to ‘const std::error_condition&’
379 | operator<(const error_condition& __lhs,
| ~~~~~~~~~~~~~~~~~~~~~~~^~~~~
a.cc:5:35: error: found ‘:’ in nested-name-specifier, expected ‘::’
5 | std::cout < "Hello world!" < std:endl;
| ^
| ::
~~~
(In GCC)
# Objects are stupid
```
std::string spurdo = "sparde"
```
where spurdo is an object
`spurdo.c_str() // converts the string to a C '\0' terminated
string.`
In C, strings are an array of chars, in C++, they're an object, with
methods.
# Compatibilty
C++ is "compatible" with C
But this can break most C programs
# A sad story about c++ executables
~~~
try to strip the executable
Did it change anything?
strip?
"strip a.out"
It removes unused stuff
like debug symbols and similar
qorg@satania ~> md5sum a.out
cd1cc93ac2ea0c8129042e96ae7d65e7 a.out
qorg@satania ~> strip a.out
qorg@satania ~> md5sum a.out
e6e6e1ea132edb67c6005e703ebe7c81 a.out
yeah?
and now compare the assembly code
how
do i disassembly it or what
how did you do it before?
g++ -S
lol
oof
maybe just compare the filesize
qorg@satania ~> gcc mtx.c -lcurses -lpthread
qorg@satania ~> du -h a.out
24K a.out
qorg@satania ~> g++ mtx.cc -lcurses -pthread
qorg@satania ~> du -h a.out
40K a.out
now with -Os
qorg@satania ~> gcc mtx.c -lcurses -lpthread -Os
qorg@satania ~> du -h a.out
24K a.out
lol
qorg@satania ~> g++ mtx.cc -lcurses -pthread -Os
qorg@satania ~> du -h a.out
24K a.out
congrats c++!
exact filesize: 23488 (according to stat)
now the stripped versions
stat'd c version: 21520
stripped c++ 14680
stripped c: 14472
a considerably smaller difference
So c++ is bloated up with debug symbols, awesome
lol
can i take a log of this and put it in kill-9.xyz/harmful/software/c++?
~~~