Sorting a string, case insensitive

I need to take in a string up to 25 characters and output them in alphabetical order (case insensitive) according to the ASCII table. I have got them sorted, but I don't know how to make the case not matter.

examples
#?34trp ===> #34?prt
I am good ===> _ _adgImoo
aBA bCB ===> _aABbBC

For example, my code would only output the last example ===> _ABCabc. I know I could change them all to capitals and then sort, but I don't know a way to change them back into lower case if there is more than one of them.

Heres the code I have written:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
    char s1[25];
    char temp;
    int i, j;
    gets(s1);
    printf(" \n %s \n", s1);





    for(j=0; s1[j]!= '\0'; j++)
    {
       for(i=0;s1[i+1]!= '\0'; i++)
       {
          if (s1[i]>s1[i+1])
          {
            temp=s1[i];
            s1[i]=s1[i+1];
            s1[i+1]=temp;

      }
  }
    
      j++;

}

  printf(" \n %s \n", s1);

    return (0);
}

Thanks for the time,
Paul

While comparing, compare toupper(char1) and toupper(char2) or lower.

So the line:
if (s1[i]>s1[i+1])

Replace it with if(toupper(s1[i] > toupper(s1[i+1]);

I dont really understand whats with the 2 loops thing in your code.

Id also suggest the swap seperated in another function for the code to be clearer when looking.

And if you want, you could check the ShellSorting method. It's much faster then the one you showed (bubblesort).