C question console application windows

[Joeado123]

Hi, I am doing a plus or minus game (I'm actually learning how to code in c) and I had a problem. When I was typing letter instead of numbers, (The menu is all right it's covered with a switch) I was trying to guess the number I got "It's Bigger!" (this is what I wrote it's normal) but written a thousand times surely. Why is it doing this and how can I write letters without the need to close the program?

 

[Joeado123]

The case 1 of my switch (might help to know what's missing)


switch(Menu)
{
case 1:
printf("\nPlus or Minus level 1: between 1 and 100");
int MAX = 100, MIN = 0;
srand(time(NULL));
number1 = (rand() % (MAX - MIN + 1)+ MIN);
printf("\nType a number between 1 and 100:");
do
{
scanf("%d", &number2);


if (number1 < number2)
{
printf("It's less!");
meter++;
}

else if (number1 > number2)
{
printf ("It's more!");
meter++;
}

else
{
printf("You found the mystery number in %d times", );
meter = 0;
printf("\nDo you want to do another game?\nIf yes type 1, or 0 to quit: ");
scanf("%d", &Replay);
}
}while(number1 != number2);

break;

 

[GerbilSoft]

If you enter a letter, it fails the "%d" specifier, so scanf() returns 0 and doesn't set number2 to anything. You might want to try this instead:

char buf[128];
fgets(buf, sizeof(buf), stdin);
number2 = (int)strtol(buf, NULL, 10);

This uses fgets() to get a string from stdin (up to 127 characters plus NULL terminator), and then uses strtol() to convert it to a number.

Note that strtol() will return 0 if it's not a valid number.

 

[Cyan]

if it still return 0 when an invalid number is entered, he will have the same result.
maybe he can use isdigit() to verify buf before calling strtol()?

edit: maybe it can only check one char at a time?