visual c++ - Updating define value in C++ -

i'm learner of c++ , i'm making assignment , can't seem update value.

it's must use define balance:

    #define balance 5000.00 

in end of statement can't seem able update balance:

    printf("deposit successful!\nyou have deposited following notes : \n");     printf("rm100 x %d = rm %.2f\n",nd100,td100);     printf("rm 50 x %d = rm %.2f\n",nd50,td50);     printf("rm 20 x %d = rm %.2f\n",nd20,td20);     printf("rm 10 x %d = rm %.2f\n\n",nd10,td10);     dtotal=td100+td50+td20+td10;     printf(" total     = rm %.2f\n\n",dtotal);     newbalance=5000+dtotal;     printf("your current balance rm %.2f\n\n",newbalance); 

i want update newbalance become balance can continue withdrawal. can show bit of withdrawal

    printf("\nwithdrawal successful!\n");     printf("%d notes x rm 50 = rm%d.00\n",wnotes,wamount);     printf("your current balance rm %.2f\n\n",newbalance); 

please give me suggestions.

you need understand how works , preprocessor in c/c++ languages. preprocessor used before program first run. used during converting program (text) machine code. want outside of preprocessor/compiler duty - part of program itself.

so if want changed during program run typically need use variables like:

double balance = 5000; 

suggested @jacdeh in comments.