Language: C++

main(){int n,if[9] = {};double a;for(scanf("%d",&n),i=n;scanf("%lf",a),i;--i)a<165?f[1]++:a<170?f[2]++:a<175?f[3]++:a<180?f[4]++:a<185?f[5]++:f[6]++;for(i=1;i<7;puts(""),++i)for(printf("%d:",i),n=0;n<f[i];++n)printf("*");}

Compiler output:
a.cc:1:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
    1 | main(){int n,if[9] = {};double a;for(scanf("%d",&n),i=n;scanf("%lf",a),i;--i)a<165?f[1]++:a<170?f[2]++:a<175?f[3]++:a<180?f[4]++:a<185?f[5]++:f[6]++;for(i=1;i<7;puts(""),++i)for(printf("%d:",i),n=0;n<f[i];++n)printf("*");}
      | ^~~~
a.cc: In function 'int main()':
a.cc:1:14: error: expected unqualified-id before 'if'
    1 | main(){int n,if[9] = {};double a;for(scanf("%d",&n),i=n;scanf("%lf",a),i;--i)a<165?f[1]++:a<170?f[2]++:a<175?f[3]++:a<180?f[4]++:a<185?f[5]++:f[6]++;for(i=1;i<7;puts(""),++i)for(printf("%d:",i),n=0;n<f[i];++n)printf("*");}
      |              ^~
a.cc:1:38: error: 'scanf' was not declared in this scope
    1 | main(){int n,if[9] = {};double a;for(scanf("%d",&n),i=n;scanf("%lf",a),i;--i)a<165?f[1]++:a<170?f[2]++:a<175?f[3]++:a<180?f[4]++:a<185?f[5]++:f[6]++;for(i=1;i<7;puts(""),++i)for(printf("%d:",i),n=0;n<f[i];++n)printf("*");}
      |                                      ^~~~~
a.cc:1:53: error: 'i' was not declared in this scope
    1 | main(){int n,if[9] = {};double a;for(scanf("%d",&n),i=n;scanf("%lf",a),i;--i)a<165?f[1]++:a<170?f[2]++:a<175?f[3]++:a<180?f[4]++:a<185?f[5]++:f[6]++;for(i=1;i<7;puts(""),++i)for(printf("%d:",i),n=0;n<f[i];++n)printf("*");}
      |                                                     ^
a.cc:1:84: error: 'f' was not declared in this scope
    1 | main(){int n,if[9] = {};double a;for(scanf("%d",&n),i=n;scanf("%lf",a),i;--i)a<165?f[1]++:a<170?f[2]++:a<175?f[3]++:a<180?f[4]++:a<185?f[5]++:f[6]++;for(i=1;i<7;puts(""),++i)for(printf("%d:",i),n=0;n<f[i];++n)printf("*");}
      |                                                                                    ^
a.cc:1:154: error: 'i' was not declared in this scope
    1 | main(){int n,if[9] = {};double a;for(scanf("%d",&n),i=n;scanf("%lf",a),i;--i)a<165?f[1]++:a<170?f[2]++:a<175?f[3]++:a<180?f[4]++:a<185?f[5]++:f[6]++;for(i=1;i<7;puts(""),++i)for(printf("%d:",i),n=0;n<f[i];++n)printf("*");}
      |                                                                                                                                                          ^
a.cc:1:162: error: 'puts' was not declared in this scope
    1 | main(){int n,if[9] = {};double a;for(scanf("%d",&n),i=n;scanf("%lf",a),i;--i)a<165?f[1]++:a<170?f[2]++:a<175?f[3]++:a<180?f[4]++:a<185?f[5]++:f[6]++;for(i=1;i<7;puts(""),++i)for(printf("%d:",i),n=0;n<f[i];++n)printf("*");}
      |                                                                                                                                                                  ^~~~
a.cc:1:179: error: 'printf' was not declared in this scope
    1 | main(){int n,if[9] = {};double a;for(scanf("%d",&n),i=n;scanf("%lf",a),i;--i)a<165?f[1]++:a<170?f[2]++:a<175?f[3]++:a<180?f[4]++:a<185?f[5]++:f[6]++;for(i=1;i<7;puts(""),++i)for(printf("%d:",i),n=0;n<f[i];++n)printf("*");}
      |                                                                                                                                                                                   ^~~~~~
a.cc:1:1: note: 'printf' is defined in header '<cstdio>'; this is probably fixable by adding '#include <cstdio>'
  +++ |+#include <cstdio>
    1 | main(){int n,if[9] = {};double a;for(scanf("%d",&n),i=n;scanf("%lf",a),i;--i)a<165?f[1]++:a<170?f[2]++:a<175?f[3]++:a<180?f[4]++:a<185?f[5]++:f[6]++;for(i=1;i<7;puts(""),++i)for(printf("%d:",i),n=0;n<f[i];++n)printf("*");}
a.cc:1:201: error: 'f' was not declared in this scope
    1 | main(){int n,if[9] = {};double a;for(scanf("%d",&n),i=n;scanf("%lf",a),i;--i)a<165?f[1]++:a<170?f[2]++:a<175?f[3]++:a<180?f[4]++:a<185?f[5]++:f[6]++;for(i=1;i<7;puts(""),++i)for(printf("%d:",i),n=0;n<f[i];++n)printf("*");}
      |                                                                                                                                                                                                         ^