c pointers referencing and dereferencing

Question

Write a program that will sort three numbers. The user will enter three numbers int variables named num1, num2 and num3. You will pass by reference these three values to a function called sortNums(), which will then put them order from smallest to largest. Num1 will hold the smallest value, num2 will hold the middle value and num3 will hold the largest value. Print the numbers in order from main().

how can i fix my if statement. when i put 123 it comes out right and when i put 321 it comes out right but when i put 213 it comes out wrong.

 //function prototype
    void sortNums(int*,int*,int*);
    int main()
    {
     //Variables   

     int num1;
     int num2;
     int num3;

     //refernce numbers variables
     int *one;
     int *two;
     int *three;

     //inputing nums

     printf("Please enter num1: \n");

     scanf("%d", &num1);

     printf("Please enter num2: \n");

     scanf("%d", &num2);

     printf("Please enter num3: \n");

     scanf("%d",&num3);
     //putting reference numbers into variables

     one = &num1;
     two = &num2;
     three = &num3;

   sortNums(one,two,three);

  printf("num1 %d\n",num1);
  printf("num2 %d\n",num2);
  printf("num3 %d\n",num3);


    getch();
    return 0;
        }
     //function   
    void sortNums(int *one,int *two, int *three)
    {
       int n1 = *one;
       int n2 = *two;
       int n3 = *three;



   if ((n1 > n2) && (n2 > n3)){
           *one = n3;
           *two = n2;
           *three = n1;
    }
    else if ((n1 > n2) &&(n2 < n3) ){
         *one = n2;
         *two = n3;
         *three = n1;
         }
    else {
         *one = n1;
         *two = n2;
         *three = n3;
              }    



    }

The only problem I see is that you are not sorting them completely. — o_weisman

Asthor Asthor · Accepted Answer · 2014-03-23T09:59:14

You're lacking some if tests.

You don't, for example, check if the n1 is bigger than n3 or smaller in your middle test. Adding an if inside the middle if would, for example, sort the the the second highest and highest value.

You are also missing a test if the first number is bigger than the 2nd number but smaller than the third number.

if ((n1 > n2) && (n2 > n3)){
    *one = n3;
    *two = n2;
    *three = n1;       
}
else if ((n1 > n2) &&(n2 < n3) ){
    if(n1 > n3) {
        *one = n2;
        *two = n3;
        *three = n1;
    } else {
        *one = n2;
        *two = n1;
        *three = n3;   
    }
} else if(n1 < n2) && (n2 > n3) {
        if(n1 > n3) {
            *one = n3;
            *two = n1;
            *three = n2;  
        } else {
            *one = n1;
            *two = n3;
            *three = n2;  
        }
} else {
    *one = n1;
    *two = n2;
    *three = n3;
}

Adding these extra if's should fix it.

You can also drop some ifs if you want, but having different if statements making the code shorter. There are also various other things you can do to improve the code. For example, you don't need to create a pointer from the ints and then you send it. You could just do sortNums(&num1,&num2,&num3);

c pointers referencing and dereferencing

1 Answers