/in/foo.cc:5:24: error: 'b' has not been declared
 float triangle(float a,b,c){
                        ^
/in/foo.cc:5:26: error: 'c' has not been declared
 float triangle(float a,b,c){
                          ^
/in/foo.cc: In function 'float triangle(float, int, int)':
/in/foo.cc:6:13: error: 'b' was not declared in this scope
  float p=(a+b+c)/2;
             ^
/in/foo.cc:6:15: error: 'c' was not declared in this scope
  float p=(a+b+c)/2;
               ^