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THis is the compare function to be used in generic sort function. x and y are the elements to be compared for generic sort function.

int CompInt(void *x, void *y)
{
  int a = *((int*)x);
  int b = *((int*)y);
  int choice;
  printf("How do you want to sort ? \n\t1. Ascending \n\t2. Descending\n");
  scanf(" %d ", &choice);
  if(choice == 1)
    {
        if(a > b) return -1;
        else return 1;
    }
  if(choice == 2)
    {
        if(a > b) return 1;
        else return -1;
    }
}

the calling function keeps calling CompInt function again and again without performing the compare. It keeps printing 

how do you want to sort?`  
1. ascending 
2. descending

Is there any way I can put an option for Ascending or Descending?

this is how I call the function

if(compareFcn(*1st element*, *2nd element*) > 0);
surjit
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1 Answers1

1

  1. I think you Should to Make a two function. If you select ascending. like this.

    int Ascending(void * a, void * b)  
{  
    int inter_a = *((int*)(a)); int inter_b = *((int*)(b));

    if(inter_a > inter_b) 
         return -1;
    else 
         return 1;
}

int Descending(void * a, void * b)  
{  
    int inter_a = *((int*)(a)); int inter_b = *((int*)(b));

    if(inter_a < inter_b) 
         return -1;
    else 
         return 1;
}

    user can Select In Main Function. use Ascending, or Descending. And You call function what user select function. 

    if(choice == 1)
{
     Sort((void*)num, Ascending, sizeof(int), max);
}
else
{
     Sort((void*)num, Descending, sizeof(int), max);
}

  2. And CompStr. I think you shold to use string.h.

CompStr has Problem. if a[i] == 'a', b[i] == 'D'. CompStr is think a[i] is comp first. you should to use like this.

    int CompStr(void *x, void *y)
    {
        char *a = (char*)x;
        char *b = (char*)y;
        int c1 = 0, c2 = 0, cmp = 0, i = 0;
        while(a[c1] != '\0') c1 += 1;
        while(b[c2] != '\0') c2 += 1;
        while((i < c1) && (i < c2))
        {  
            char compA = tolower(a[i]);
            char compB = tolower(b[i]);
            if(compA == compB)
            {
                 i++;
                 continue;
            }
            if(compA < compB)
            {
                 cmp = (-1);
                 break;
            }
            if(compA > compB)
            {
                 cmp = 1;
                 break;
            }
         }
         return cmp;
     }

and Test Code = 

int main()
{
    //first exmaple.
    char * str1 = "Hallo.";
    char * str2 = "Hello.";

    //second exmaple.
    char * str3 = "What Does Fox Say?";
    char * str4 = "IDOLM@STER";

    //third example.
    char * str5 = "Stack Overflow.";
    char * str6 = "Stack Overflow.";

    int result = CompStr((void *)str1, (void *)str2);

    int result1 = CompStr((void *)str3, (void *)str4);

    int result2 = CompStr((void*)str5, (void*)str6);

    printf("1 : %d\n", result);
    printf("2 : %d\n", result1);
    printf("3 : %d", result2);
    return 0;
}

output is 1 : -1 2: 1 3: 0 Code is work well.

this code has problem. 

case 4:
{
    printf("How many Strings you want to sort ? ");
    scanf("%d", &max);
    printf("Enter the strings\n");
    for (i = 0; i < max; i++) scanf(" %s", str[i]);
    Sort((void*)str, CompStr, sizeof(char), max);
    printf("Sorted elements are are - \n");
    for (i = 0; i < max; i++) printf(" %s\n", str[i]);
    break;
}

you want compare string. but sizeof element is just 1 byte. and youre code cant compile.

void *mem_copy(void *dest, const void *src, unsigned int n)
{
    int i;
    char* newsrc = (char*)src;
    char* newdest = (char*)dest;
    for (i = 0; i < n; i++) 
    newdest[i] = newsrc[i];
}

i use compile VS 2017, you write return type is void *, but function is dosen`t return. is right code? please modified code compile well.

Perfect Normally
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