SRL Archive - C/C++ Help and Tutorials

I have to 'Write a program in C that displays a reversed number' (if you input 4567 the output should be 7654). I googled this and found that using strings or arrays would make it easy, but I haven't learned how to use those yet so I suppose I'm not supposed to use them. Here is what I have so far…

int main()
{
	int num1, reversed, num3, original, num5, lastnum;

		printf("Please enter an integer: ");
	        num1 = GetInteger();
		original = num1;
		num5 = numdigits(num1); //numdigits is a function that finds the amount of digits
                reversed = 0;
		lastnum = num1 - ((num1/10)*10);
		reversed = lastnum;
		while(num5 > 1)
		{
			num1 = (original / 10) - ((original / 100) * 10);
		        reversed = (reversed * 10) + num1;
			num5 = num5 - 1;
		}



		printf("The reverse of %d is: %d\n", original, reversed);
}

I'm having trouble with the loop. I'm not doing it for any specific amount of digits, so I can't do this

		while(num5 > 1)
		{
			num1 = (original / 10) - ((original / 100) * 10);
		        reversed = (reversed * 10) + num1;
                        num1 = (original /100) - ((original /1000) * 100);
                        reversed = (reversed * 100) + num1;
//etc..............
			num5 = num5 - 1;
		}

I can't figure out how to make it so that it'll work for any amount of digits….

int reverse(long num)
{
   long result=0,temp=num,k;
   int a=0,i;
   
   for(;temp/10!=0;temp/=10)   //finds the number or digits   
       a++;

   for(;num/10!=0;num/=10,a--)
     {
        k=num%10;
        for(i=0;i<a;i++)
          {
             k*=10;
          }
         result+=k;
     }

   return result;

}

Found off google, didn't bother to think.. Should help.

Ok….Now it works for 2 and 3 digits but not for 4+ digits… I wrote the program out on paper and I got the correct answer with 4 digits (I guess I missed something…). What's making it not work?

int main()
{
	int digit, digit2, reversed, original, numofdig, lastnum, num1, num2;

		printf("Please enter an integer: ");
	        original = GetInteger();
		digit = original;
		numofdig = numdigits(original); 
                reversed = 0;
        
		lastnum = original%10;    
		reversed = lastnum;

		num1 = 10;
		num2 = 100;
		digit2 = digit;
		while(numofdig > 1) [B][U]
		{
			digit2 = (original / num1) - ((original / num2) * num1);
			reversed = (reversed * 10) + digit2;
			digit2 = digit;
                        num1 = num1*10;
		        num2 = num2*10;
			numofdig-=1;
		}




		printf(" The reverse of %d is : %d\n", original, reversed);
}