docs/examples/demo/demo.hpp:6:11: warning: [modernize-use-default-member-init]

use default member initializer for 'useless'

 char* useless;
 ^
 {"0円"}

docs/examples/demo/demo.hpp:7:9: warning: [modernize-use-default-member-init]

use default member initializer for 'numb'

 int numb;
 ^
 {0}

docs/examples/demo/demo.hpp:11:11: warning: [modernize-use-trailing-return-type]

use a trailing return type for this function

 void *not_useful(char *str){useless = str;}
 ~~~~~~^
 auto -> void *

docs/examples/demo/demo.cpp:3:10: warning: [modernize-deprecated-headers]

inclusion of deprecated C++ header 'stdio.h'; consider using 'cstdio' instead

#include <stdio.h>
 ^~~~~~~~~
 <cstdio>

docs/examples/demo/demo.cpp:8:5: warning: [modernize-use-trailing-return-type]

use a trailing return type for this function

int main(){
~~~ ^
auto -> int

docs/examples/demo/demo.cpp:10:13: warning: [readability-braces-around-statements]

statement should be inside braces

 for (;;) break;
 ^
 {

docs/examples/demo/demo.cpp:13:5: warning: [cppcoreguidelines-pro-type-vararg]

do not call c-style vararg functions

 printf("Hello world!\n");
 ^