foo.cc: In function ‘int main()’:
foo.cc:8:14: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
    8 |         if(ch='+')
      |            ~~^~~~
foo.cc:10:14: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
   10 |         if(ch='-')
      |            ~~^~~~