/in/foo.c: In function 'main':
/in/foo.c:6:29: error: 'c' undeclared (first use in this function)
    6 |     scanf("%d,%d,%d",&a,&b,&c);
      |                             ^
/in/foo.c:6:29: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:7:9: error: 'sum1' undeclared (first use in this function)
    7 |         sum1=a+b;
      |         ^~~~
/in/foo.c:8:9: error: 'sum2' undeclared (first use in this function)
    8 |         sum2=b+c;
      |         ^~~~
/in/foo.c:9:9: error: 'sum3' undeclared (first use in this function)
    9 |         sum3=a+c;
      |         ^~~~
/in/foo.c:12:12: error: 'C' undeclared (first use in this function)
   12 |            C=a+b+c;
      |            ^
/in/foo.c:5:13: warning: unused variable 'c\U0000ff0cC' [-Wunused-variable]
    5 |     int a,b,c，C;
      |             ^~~~