下列程序的输出结果是______。 #include sub1(char a,char b) {char c; c=a;a=b;b=c;} sub2(char* a,char b) {char c; c=*a;*a=b;b=c;} sub3(char* a,char*b) {char c; c=*a;*a=*b;*b=c;} { char a,b; a='A' ;b='B'; sub3 (&a, &b) ;putchar (a) ;putchar (b); a='A';b='B';sub2(&a,b);putchar(a);prtchar(b); a='A';b='B';sub1(a,b);putchar(a) ;putchar(b); }