/in/foo.c:5:1: error: unknown type name 'using'
 using namespace std;
 ^~~~~
/in/foo.c:5:17: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'std'
 using namespace std;
                 ^~~
/in/foo.c: In function 'main':
/in/foo.c:31:17: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'char (*)[100]' [-Wformat=]
         scanf("%s %d %d %c %c %d",&student[i].name,&student[i].finalgrade,
                 ^