c-gcc, 68 bytes

Result

AC

Code [DL]

#include<string.h>
s[1];main(){qsort(gets(s),100,1,strcmp);puts(s);}

stdin

2693901189686399823831909478799635700953827419463170475212225903885547284593906972079030558522992760

stdout

0000000000011111122222222222233333333334444445555555555666666677777777778888888888999999999999999999

stderr

/tmp/code.c:2:1: warning: data definition has no type or storage class
 s[1];main(){qsort(gets(s),100,1,strcmp);puts(s);}
 ^
/tmp/code.c:2:1: warning: type defaults to ‘int’ in declaration of ‘s’ [-Wimplicit-int]
/tmp/code.c:2:6: warning: return type defaults to ‘int’ [-Wimplicit-int]
 s[1];main(){qsort(gets(s),100,1,strcmp);puts(s);}
      ^
/tmp/code.c: In function ‘main’:
/tmp/code.c:2:13: warning: implicit declaration of function ‘qsort’ [-Wimplicit-function-declaration]
 s[1];main(){qsort(gets(s),100,1,strcmp);puts(s);}
             ^
/tmp/code.c:2:19: warning: implicit declaration of function ‘gets’ [-Wimplicit-function-declaration]
 s[1];main(){qsort(gets(s),100,1,strcmp);puts(s);}
                   ^
/tmp/code.c:2:41: warning: implicit declaration of function ‘puts’ [-Wimplicit-function-declaration]
 s[1];main(){qsort(gets(s),100,1,strcmp);puts(s);}
                                         ^
/tmp/ccrmFVtC.o: In function `main':
code.c:(.text.startup+0xc): warning: the `gets' function is dangerous and should not be used.

strace