/in/foo.c: In function 'main':
/in/foo.c:7:5: error: invalid suffix "x" on integer constant
   y=3x-1;
     ^~
/in/foo.c:9:5: error: invalid suffix "x" on integer constant
   y=2x^2=4-5;
     ^~
/in/foo.c:11:6: error: invalid suffix "x" on integer constant
   y=(5x+10)^(0.5);
      ^~
/in/foo.c:13:4: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses]
   y==x^3;
   ~^~~
/in/foo.c:13:7: warning: statement with no effect [-Wunused-value]
   y==x^3;
   ~~~~^~
/in/foo.c:14:16: warning: format '%f' expects argument of type 'double', but argument 2 has type 'float *' [-Wformat=]
     printf("%.3f",&y);
                ^