Variable definition is a strange problem.

[Cpp] # include "stdio. h "# include <string> int add () {int a; int B = 2; a = a + B; printf (" % d \ n ", ); return 0;} void cat () {char st1 [] = "bbbbbbb"; char tt [50]; strcat (tt, st1); printf ("% s \ n ", tt);} int main () {// loop body definition is defined only once during compilation. The space is the same space for (int j = 0; j <2; j ++) {char st1 [] = "bbbbbbbbb"; char tt [50]; strcat (tt, st1); printf ("% s \ n in loop ", tt);} printf ("\ n"); // The address space is not changed, but the content is cleared, it's amazing !???????????????!! For (int I = 0; I <3; I ++) {cat (); add ();} printf ("\ n"); // contains the cyclic body, the address space is cleared. // If the method is not cleared, the variables are in the same space. Cat (); {cat ();} printf ("\ n"); // The variable space with the same name cannot be reached. {char st1 [] = "bbbbbbb "; char tt [50]; strcat (tt, st1); printf ("small scope 1% s \ n", tt) ;}{ char st1 [] = "bbbbbbb "; char tt [50]; strcat (tt, st1); printf ("small scope 2% s \ n", tt);} return 0;} Be sure to initialize the variables, clear it @!