Question

Is there a way to store user inputs in switch case from one operation and use it across switch operations at run-time.

Example: If its a software for a Bank and I want to take information from the user and validate if his a/c number is correct and also check if he has enough bank balance to withdraw money.

I need to know how to store the value of one operation,so that I could use it for further ops.

 switch(ops)
    {

                            char ac_no;
                            long amt,amt2,init_dep;
                            char name,ac_allocated;


            case OpenAC:
                    {
                            printf("1.Name:\n");
                            scanf("%s",&name);

                            printf("2.A/Cno_allocated:\n");
                            scanf("%s",&ac_allocated);

                            printf("3.Initial deposit:\n");
                            scanf("%d",&init_dep);
                            break;

                    }
            case Deposit:
                    {
                            printf("Enter the a/c number: ");
                            scanf("%s",&ac_no);

                            printf("Amount:Rs. ");
                            scanf("%ld",&amt);
                            break;

                    }
            case Withdraw:
                    {
                            printf("Enter the a/c number: ");
                            scanf("%s",&ac_no);

                            printf("Amount:Rs. ");
                            scanf("%ld",&amt2);


                  {printf("Cannot withdraw.Rs.500 minimum balance mandatory.\n");}

                            break;

                    }
            return ops;

    }

I also tried declaring variables in the switch(ops) to store the value in them(like in the following case to validate the a/c number in the next step but it doesn’t help.)

Edited code:

`

                            char ac_no;

                            long amt,amt2,init_dep,dep1;

                            char name,ac_allocated,ac1;

               case OpenAC:
                    {
                            printf("1.Name:\n");
                            scanf("%s",&name);

                            printf("2.A/Cno_allocated:\n");
                            scanf("%s",&ac_allocated);

                            ac_allocated = ac1;

                            printf("3.Initial deposit:\n");
                            scanf("%d",&init_dep);
                            init_dep = dep1;

                            //break;

                    }
            case Deposit:
                    {
                            printf("Enter the a/c number: ");
                            scanf("%s",&ac_no);

                            if(ac_no == ac1)
                            {
                             printf("Amount:Rs. ");
                             scanf("%ld",&amt);
                            }

                            break;

`

Answer 1

First issue: you’re using the wrong type for ac_no, name, ac_allocated, and ac1. You’re obviously wanting to store strings at these locations, so instead of a plain char, you need to declare arrays of char:

char ac_no[AC_NO_SIZE];
char name[NAME_SIZE];
char ac_allocated[AC_ALLOCATED_SIZE];
char ac1[AC1_SIZE];

where each *_SIZE is large enough to hold your input data plus 1 extra character for the 0 terminator. IOW, if your account numbers are at most 10 characters long, AC_NO_SIZE needs to be 11.

Second issue: do not declare variables at the head of a switch statement; any initializations will be skipped.

Third issue: auto variables declared inside a specific scope will not be available outside of that scope; they will cease to exist when that scope exits. None of the variables you declare will be available outside of the switch statement.

Fourth issue: if this switch operation is inside of a function, and you want to preserve these values between function calls, you can do one of three things:

• Declare these items at file scope, outside of any function (not recommended):

  
  char ac_no[AC_NO_SIZE];
  char name[NAME_SIZE];
  char ac_allocated[AC_ALLOCATED_SIZE];
  char ac1[AC1_SIZE];
  long amt, amt2, init_dep;
  
  void foo()
  {
     int ops;
     ...
     ops = bar(ops);
     ...
  }
  
  int bar(int ops)
  {
    switch(ops)
    {
      case OpenAC:
        printf("Name: ");
        fflush(stdout);
        scanf("%s", name); // note no &; true for all char [] types
        printf("A/C no allocated: ");
        fflush(stdout);
        scanf("%s", ac_allocated);
        printf("Initial deposit: ");
        fflush(stdout);
        scanf("%ld", &init_dep);
        ...
    }
    return ops;
    ...
  

• Declare these items as `static` in the function (slightly less recommended); they will not be visible outside of the function, but their value will be retained between function calls:

  
  int bar(int ops)
  {
    static char ac_no[AC_NO_SIZE];
    static char name[NAME_SIZE];
    static char ac_allocated[AC_ALLOCATED_SIZE];
    static char ac1[AC1_SIZE];
    static long amt, amt2, init_dep;
  
    switch(ops)
    {
      case OpenAC:
        printf("Name: ");
        fflush(stdout);
        scanf("%s", name);
        printf("A/C no allocated: ");
        fflush(stdout);
        scanf("%s", ac_allocated);
        printf("Initial deposit: ");
        fflush(stdout);
        scanf("%ld", &init_dep);
      ...
    }
    return ops;
  }
  

• Declare these items in the calling function and pass them as parameters to this function (recommended):

  
  int foo(int ops, 
          char *ac_no, 
          char *name, 
          char *ac_allocated, 
          char *ac1, 
          long *amt,          // Since these values are being modified in the function,
          long *amt2,         // we must pass pointers to them, otherwise the changes
          long *init_dep)     // will not be reflected in the calling function
  {
    switch(ops)
    {
       case OpenAC:
         printf("Name: ");
         fflush(stdout);
         scanf("%s", name); // no & before name; same is true for rest of parameters
         printf("A/C no allocated: ");
         fflush(stdout);
         scanf("%s", ac_allocated);
         printf("Initial deposit: ");
         fflush(stdout);
         scanf("%ld", init_dep); // no & before init_dep since it's already a pointer
         ...
  

All of this assumes I’m understanding your problem correctly.