c-gcc, 57 bytes

Result

AC

Code [DL]

s[1];main(){strcmp(qsort(gets(s),100,1,strcmp));puts(s);}

stdin

8426419695744233099984159659650648315131365629770836997433693829219873590489335759189370500715914765

stdout

0000000111111111222223333333333333444444444555555555555666666666677777777788888888999999999999999999

stderr

/tmp/code.c:1:1: warning: data definition has no type or storage class
 s[1];main(){strcmp(qsort(gets(s),100,1,strcmp));puts(s);}
 ^
/tmp/code.c:1:1: warning: type defaults to ‘int’ in declaration of ‘s’ [-Wimplicit-int]
/tmp/code.c:1:6: warning: return type defaults to ‘int’ [-Wimplicit-int]
 s[1];main(){strcmp(qsort(gets(s),100,1,strcmp));puts(s);}
      ^
/tmp/code.c: In function ‘main’:
/tmp/code.c:1:13: warning: implicit declaration of function ‘strcmp’ [-Wimplicit-function-declaration]
 s[1];main(){strcmp(qsort(gets(s),100,1,strcmp));puts(s);}
             ^
/tmp/code.c:1:20: warning: implicit declaration of function ‘qsort’ [-Wimplicit-function-declaration]
 s[1];main(){strcmp(qsort(gets(s),100,1,strcmp));puts(s);}
                    ^
/tmp/code.c:1:26: warning: implicit declaration of function ‘gets’ [-Wimplicit-function-declaration]
 s[1];main(){strcmp(qsort(gets(s),100,1,strcmp));puts(s);}
                          ^
/tmp/code.c:1:49: warning: implicit declaration of function ‘puts’ [-Wimplicit-function-declaration]
 s[1];main(){strcmp(qsort(gets(s),100,1,strcmp));puts(s);}
                                                 ^
/tmp/ccMPFnUt.o: In function `main':
code.c:(.text.startup+0xc): warning: the `gets' function is dangerous and should not be used.

strace