C Question

C scanf unsigned long values

I wrote this piece of code, but cases 2 and 3 seem to have a problem. As noted in the title I think it has to do with unsigned long operations, but I can't understand what it is exactly.

*Edited version (scanf changes).

#include <stdio.h>
int main()
{
int pin, inp, count=0;
unsigned dep=100, add, withdraw;
start:;
if (count>0)
{
printf("\n");
}
printf("Please, input your PIN number:");
scanf("%i", &pin);
while (5)
{
if (pin==2014)
{
printf("To view your deposit, press 1.\n");
printf("To add money to your deposit, press 2.\n");
printf("To withdraw money from your deposit, press 3.\n");
printf("To log off, press 4.\n");
scanf("%i", &inp);
switch(inp)
{
case 1:
printf("The remainder of your deposit is %i.\n\n", dep);
break;
case 2:
printf("Enter the amount of money you want to add: ");
scanf("%u", add);
dep+=add;
break;
case 3:
printf("Enter the amount of money you want to withdraw. We would like to remind you that it should be multiple of 20.\n");
scanf("%u", withdraw);
if(((withdraw)%20==0)&&(withdraw<dep))
{
dep-=withdraw;
}
else
{
printf("We are sorry, but you either chose an invalid withdraw amount or you tried to withdrw more money than you have deposited.\n");
}
break;
case 4:
printf("Logging off.\n");
goto end;
break;

}
}
else
{
printf("You entered an invalid PIN.");
count++;
goto start;

}

}
end:;
}

Answer

You're not using scanf correctly. scanf("%lu", add); For "%lu" it expects a pointer to an unsigned long int, but what you're passing is not a pointer and not an unsigned long int. Try: scanf("%u", &add); Or change add's type. I'd also recommend checking scanf's returned value. See: Value returned by scanf function in c

Comments