/in/foo.c: In function 'main':
/in/foo.c:12:39: warning: operation on 'j' may be undefined [-Wsequence-point]
         if((c[j]>='0')&&(c[j]<='9'))a[++j]=c[j]-'0';
                                       ^~~
/in/foo.c:13:16: warning: operation on 'j' may be undefined [-Wsequence-point]
         else a[++j]=c[j]-'A'+10;
                ^~~