/in/foo.c: In function 'main':
/in/foo.c:7:4: error: expected ',' or ';' before 'int'
    int i;
    ^~~
/in/foo.c:10:8: error: 'i' undeclared (first use in this function)
    for(i=1;i<=n'i++)
        ^
/in/foo.c:10:8: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:10:16: warning: missing terminating ' character
    for(i=1;i<=n'i++)
                ^
/in/foo.c:10:16: error: missing terminating ' character
    for(i=1;i<=n'i++)
                ^~~~~
/in/foo.c:11:5: error: expected ';' before '{' token
     {
     ^
/in/foo.c:19:1: error: expected expression before '}' token
 }
 ^
/in/foo.c:19:1: error: expected expression before '}' token
/in/foo.c:8:23: warning: unused variable 'c' [-Wunused-variable]
    double a=2.0,b=1.0,c=0;
                       ^
/in/foo.c:8:17: warning: unused variable 'b' [-Wunused-variable]
    double a=2.0,b=1.0,c=0;
                 ^
/in/foo.c:8:11: warning: unused variable 'a' [-Wunused-variable]
    double a=2.0,b=1.0,c=0;
           ^
/in/foo.c:6:11: warning: unused variable 'sum' [-Wunused-variable]
    double sum=0
           ^~~