foo.cc: In function ‘int main()’:
foo.cc:9:14: error: invalid conversion from ‘const char*’ to ‘int’ [-fpermissive]
    9 |         if(c="+")
      |              ^~~
      |              |
      |              const char*
foo.cc:9:13: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
    9 |         if(c="+")
      |            ~^~~~
foo.cc:13:19: error: invalid conversion from ‘const char*’ to ‘int’ [-fpermissive]
   13 |         else if(c="-")
      |                   ^~~
      |                   |
      |                   const char*
foo.cc:13:18: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
   13 |         else if(c="-")
      |                 ~^~~~
foo.cc:18:17: error: break statement not within loop or switch
   18 |                 break;
      |                 ^~~~~