foo.cpp:7:23: error: empty character constant
 if(b==')'||a=='/'||a==''||b=='+'||b=='-')return 1;
                       ^
foo.cpp:14:8: error: empty character constant
 if(ch=='')return (ab)%10000;
        ^
foo.cpp: In function 'int cal(int, char, int)':
foo.cpp:14:19: error: 'ab' was not declared in this scope
 if(ch=='')return (ab)%10000;
                   ^
foo.cpp: In function 'int main()':
foo.cpp:23:9: warning: array subscript has type 'char' [-Wchar-subscripts]
 b[++b[0]]='(';
         ^
foo.cpp:28:31: error: 't10' was not declared in this scope
 while(s[k]>='0'&&s[k]<='9'){t=t10+s[k]-'0';k++;}
                               ^
foo.cpp:31:18: warning: array subscript has type 'char' [-Wchar-subscripts]
 bj=Compare(b[b[0]],s[k]);
                  ^
foo.cpp:31:24: error: 'Compare' was not declared in this scope
 bj=Compare(b[b[0]],s[k]);
                        ^
foo.cpp:33:31: warning: array subscript has type 'char' [-Wchar-subscripts]
 a[a[0]-1]=Cal(a[a[0]-1],b[b[0]],a[a[0]]);
                               ^
foo.cpp:33:40: error: 'Cal' was not declared in this scope
 a[a[0]-1]=Cal(a[a[0]-1],b[b[0]],a[a[0]]);
                                        ^
foo.cpp:38:20: warning: array subscript has type 'char' [-Wchar-subscripts]
 if(bj==-1){b[++b[0]]=s[k];k++;}
                    ^
foo.cpp: In function 'int cal(int, char, int)':
foo.cpp:16:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^