开关盒操作员 - C.

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

Why not declare your variables outside the switch. You could even put braces around the switch to prevent the variables from leaking to the surrounding function, like this:

// code from the surrounding function
{
char ac_no; 
long amt,amt2,init_dep; 
char name,ac_allocated; 

switch(ops) 
   { 
   case OpenAC: 
      ...
   }
} // end of block

Answer 2

我不确定我是否理解你的问题，但是如果你在switch语句的大括号内声明了某些内容，当你点击结束的大括号时它将超出范围，并且在下次遇到switch语句时不可用。

Answer 3

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.

Answer 4

Maybe you should use structure to hold account data and functions to make it readable and maintainable.

struct account_s { /* Fields borrowed to @John Bode */
    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;
};

int openAC(struct account_s *account);

to be continued... :)