While,switch, case statement - c

Question

I'm using a while, switch, case statement for my menu and when it runs it keeps saying enter choice, I know while(1) creates an infinite loop but is there a way to avoid this?
while(1)
{
printf("\nEnter Choice \n");
scanf("%d",&i);
switch(i)
{
case 1:
{
printf("Enter value to add to beginning: ");
scanf("%c",&value);
begin(value);
display();
break;
}
case 2:
{
printf("Enter value to add last: ");
scanf("%c",&value);
end(value);
display();
break;
}
case 3:
{
printf("Value to enter before\n");
scanf("%c",&loc);
printf("Enter value to add before\n");
scanf("%c",&value);
before(value,loc);
display();
break;
}
case 4 :
{
display();
break;
}
}
}
Any help would be appreciated.

Answer 1

While(1) is ok. But you have to have some conditions to finish the loop. Like :
while(1){
.........
if(i == 0)
break;
............
}
Add a space at the beginning of every "%d" and "%c",because scanf always leaves a newline characters in buffer:
"%d"->" %d"
"%c"->" %c"

Answer 2

Alternative solution,
int i = !SOME_VALUE;
while(i != SOME_VALUE)
{
printf("\n\nEnter Choice ");
scanf("%d",&i);
switch(i)
{
case SOME_VALUE: break;
.
.
.
// the rest of the switch cases
}
}
SOME_VALUE is any integer number notify to stop loop.

Answer 3

Alternatively, you may want to put a condition in the loop that relates to the input, e.g.
do
{
printf("\n\nEnter Choice ");
scanf("%d",&i);
// the rest of the switch is after this
} while (i != SOME_VALUE);
Note the use of the do loop, which tests the condition at the end, after a value has been read into i.

Answer 4

I would probably write a function that can be called in the loop:
while ((i = prompt_for("Enter choice")) != EOF)
{
switch (i)
{
case ...
}
}
And the prompt_for() function might be:
int prompt_for(const char *prompt)
{
int choice;
printf("%s: ", prompt);
if (scanf("%d", &choice) != 1)
return EOF;
// Other validation? Non-negative? Is zero allowed? Retries?
return choice;
}
You can also find relevant discussion at:
scanf() validation.
What is the reason for error while returning a structure in this C program?
Common macro to read input data and check its validity