Language: C++

#include <bits/stdc++.h>
main(){char* s[]={"light fly","fly","bantam","feather","light","light welter","welter","light middle","middle","light heavy","heavy"};float f[]={48.0,51.0,54.0,57.0,60.0,64.0,69.0,75.0,81.0,91.0,1e9};float a;while(cin>>a)for(int i=0;;i++)if(a<=f[i]){printf("%s\n",s[i]);break;}}

Compiler output:
a.cc:2:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
    2 | main(){char* s[]={"light fly","fly","bantam","feather","light","light welter","welter","light middle","middle","light heavy","heavy"};float f[]={48.0,51.0,54.0,57.0,60.0,64.0,69.0,75.0,81.0,91.0,1e9};float a;while(cin>>a)for(int i=0;;i++)if(a<=f[i]){printf("%s\n",s[i]);break;}}
      | ^~~~
a.cc: In function 'int main()':
a.cc:2:19: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
    2 | main(){char* s[]={"light fly","fly","bantam","feather","light","light welter","welter","light middle","middle","light heavy","heavy"};float f[]={48.0,51.0,54.0,57.0,60.0,64.0,69.0,75.0,81.0,91.0,1e9};float a;while(cin>>a)for(int i=0;;i++)if(a<=f[i]){printf("%s\n",s[i]);break;}}
      |                   ^~~~~~~~~~~
a.cc:2:31: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
    2 | main(){char* s[]={"light fly","fly","bantam","feather","light","light welter","welter","light middle","middle","light heavy","heavy"};float f[]={48.0,51.0,54.0,57.0,60.0,64.0,69.0,75.0,81.0,91.0,1e9};float a;while(cin>>a)for(int i=0;;i++)if(a<=f[i]){printf("%s\n",s[i]);break;}}
      |                               ^~~~~
a.cc:2:37: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
    2 | main(){char* s[]={"light fly","fly","bantam","feather","light","light welter","welter","light middle","middle","light heavy","heavy"};float f[]={48.0,51.0,54.0,57.0,60.0,64.0,69.0,75.0,81.0,91.0,1e9};float a;while(cin>>a)for(int i=0;;i++)if(a<=f[i]){printf("%s\n",s[i]);break;}}
      |                                     ^~~~~~~~
a.cc:2:46: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
    2 | main(){char* s[]={"light fly","fly","bantam","feather","light","light welter","welter","light middle","middle","light heavy","heavy"};float f[]={48.0,51.0,54.0,57.0,60.0,64.0,69.0,75.0,81.0,91.0,1e9};float a;while(cin>>a)for(int i=0;;i++)if(a<=f[i]){printf("%s\n",s[i]);break;}}
      |                                              ^~~~~~~~~
a.cc:2:56: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
    2 | main(){char* s[]={"light fly","fly","bantam","feather","light","light welter","welter","light middle","middle","light heavy","heavy"};float f[]={48.0,51.0,54.0,57.0,60.0,64.0,69.0,75.0,81.0,91.0,1e9};float a;while(cin>>a)for(int i=0;;i++)if(a<=f[i]){printf("%s\n",s[i]);break;}}
      |                                                        ^~~~~~~
a.cc:2:64: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
    2 | main(){char* s[]={"light fly","fly","bantam","feather","light","light welter","welter","light middle","middle","light heavy","heavy"};float f[]={48.0,51.0,54.0,57.0,60.0,64.0,69.0,75.0,81.0,91.0,1e9};float a;while(cin>>a)for(int i=0;;i++)if(a<=f[i]){printf("%s\n",s[i]);break;}}
      |                                                                ^~~~~~~~~~~~~~
a.cc:2:79: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
    2 | main(){char* s[]={"light fly","fly","bantam","feather","light","light welter","welter","light middle","middle","light heavy","heavy"};float f[]={48.0,51.0,54.0,57.0,60.0,64.0,69.0,75.0,81.0,91.0,1e9};float a;while(cin>>a)for(int i=0;;i++)if(a<=f[i]){printf("%s\n",s[i]);break;}}
      |                                                                               ^~~~~~~~
a.cc:2:88: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
    2 | main(){char* s[]={"light fly","fly","bantam","feather","light","light welter","welter","light middle","middle","light heavy","heavy"};float f[]={48.0,51.0,54.0,57.0,60.0,64.0,69.0,75.0,81.0,91.0,1e9};float a;while(cin>>a)for(int i=0;;i++)if(a<=f[i]){printf("%s\n",s[i]);break;}}
      |                                                                                        ^~~~~~~~~~~~~~
a.cc:2:103: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
    2 | main(){char* s[]={"light fly","fly","bantam","feather","light","light welter","welter","light middle","middle","light heavy","heavy"};float f[]={48.0,51.0,54.0,57.0,60.0,64.0,69.0,75.0,81.0,91.0,1e9};float a;while(cin>>a)for(int i=0;;i++)if(a<=f[i]){printf("%s\n",s[i]);break;}}
      |                                                                                                       ^~~~~~~~
a.cc:2:112: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
    2 | main(){char* s[]={"light fly","fly","bantam","feather","light","light welter","welter","light middle","middle","light heavy","heavy"};float f[]={48.0,51.0,54.0,57.0,60.0,64.0,69.0,75.0,81.0,91.0,1e9};float a;while(cin>>a)for(int i=0;;i++)if(a<=f[i]){printf("%s\n",s[i]);break;}}
      |                                                                                                                ^~~~~~~~~~~~~
a.cc:2:126: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
    2 | main(){char* s[]={"light fly","fly","bantam","feather","light","light welter","welter","light middle","middle","light heavy","heavy"};float f[]={48.0,51.0,54.0,57.0,60.0,64.0,69.0,75.0,81.0,91.0,1e9};float a;while(cin>>a)for(int i=0;;i++)if(a<=f[i]){printf("%s\n",s[i]);break;}}
      |                                                                                                                              ^~~~~~~
a.cc:2:215: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    2 | main(){char* s[]={"light fly","fly","bantam","feather","light","light welter","welter","light middle","middle","light heavy","heavy"};float f[]={48.0,51.0,54.0,57.0,60.0,64.0,69.0,75.0,81.0,91.0,1e9};float a;while(cin>>a)for(int i=0;;i++)if(a<=f[i]){printf("%s\n",s[i]);break;}}
      |                                                                                                                                                                                                                       ^~~
      |                                                                                                                                                                                                                       std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:146,
                 from a.cc:1:
/usr/include/c++/14/iostream:62:18: note: 'std::cin' declared here
   62 |   extern istream cin;           ///< Linked to standard input
      |                  ^~~