While loop simple problem and optimization code

/* #include <stdio.h>int main ()   {        int  I,X,Y;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;SCANF ("%d", &i);      for (x=1 ; x<=sizeof (i); x + +)     {       while (i>0)         {          y=i%10;            i=i/10;          printf ("%d ", y);         }      }  printf ("\ n");    return 0; } *//* #include <stdio.h>  int main () {   int i,a,x=0,count=0;    for (i=1;i<=100;i++ )    {      int a=i;  while (a>0)      {        x=a%10;        a=a/10;         if (x==9)         count++;       }    }   printf ("%d\n", Count);    return 0;} */Request Greatest common divisor/* #include <stdio.h>int main () {   int i,a,b;   scanf ("%d  %d ", &a,&b);  if (a>b)     i=b;  else    i =a;    for (i;i>=2;i--)    {       if (a %i==0&&b%i==0)          break;    }     printf ("%d\n", i);   return 0;} */uppercase for lowercase, lowercase for uppercase, no change, CTRL + Z jump out/* #include <stdio.h>int  main () {   char c,s;   c=getchar ();    wHile (c!=eof)    {       if (c>= ' a ' &&c<= ' Z ')        {         s=c-32;            printf ("%c\n", s);          }      else       if ( c>= ' A ' &&c<= ' Z ')           {            s=c+32;            printf ("%c\n", s);         }      else if (c>= ' 0 ' &&c<= ' 9 ')          {   s=c;          printf ("%c\n", s);             }            c=getchar ();      }     return  0;} */with pointer size/* #include <stdio.h>int main () {  int a=2,b=3;   int *pa,* pb;   pa=&a;   pb=&b;  printf ("%d %d \n%d %d\n" , A,B,*PA,*PB);     return 0;} *//* #include <stdio.h>   int main ()    {        int a,b;        int *pa,*pb;    &NBSP;&NBSP;&NBSP;&NBSP;SCANF ("%d%d", &a,&b);        pa=&a;        pb=&b;         if (A &LT;B)           {           int *tmp=pa;            pa=pb;           pb=tmp;            }       printf ("%d  %d   %d   %d\n ", *pa,*pb,a,b);       return 0;     }*/ /* #include <stdio.h>   void swap (int *a,int &NBSP;*B)        {            if (*a<*b)               {                int tmp=*a;                 *a=*b;                   *b=tmp;                    }          }   int main ()    {         int a,b;         int *pa,*pb; &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;SCANF ("%d%d", &a,&b);         pa=&a;          pb=&b;            swap (PA,PB);          return 0;    }*/Greatest common divisor/* #include <stdio.h> int main () {   &NBSP;&NBSP;INT&NBSP;A,B,I;&NBSP;&NBSP;&NBSP;SCANF ("%d%d", &a,&b);   if (a<b)       {       i=a;       a=b;        b=i;       }      if (a%b==0 )         printf ("%d", b);         else              {                 while (a%b!=0)                  {                       i= a%b;                       a=b;                       b=i;                  }                  printf ("%d\n", i);                 }                  return 0;    }*/

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While loop simple problem and optimization code