C / C++ / MFC

for(int i = 0 ; i < 100 ; i++)
{
   for(int j = 0 ; j < 100 ; j++)
   {
      fprintf(outClientFile,"%0*d%0*d\n",2,i,2,j);
   }
}

char cCharacter1, cCharacter2;

for(cCharacter1 = 'A'; cCharacter1 <= 'Z'; cCharacter1++)
{
   for(cCharacter2 = 'A'; cCharacter2 <= 'Z'; cCharacter2++)
   {
      printf("%c%c\n", cCharacter1, cCharacter2);
   }
}

char string1[] = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q',
'R','S','T','U','V','W','X','Y','Z','\0'};
int len = strlen(string1);
for (int i = 0; i < len ; i++)
{
 for (int j = 0; j < len ; j++)
 {
  fprintf(outClientFile,"%c%c\n",string1[i],string1[j]);
 }
 }
}