Compilare: user.c: In function ‘main’: user.c:9:5: warning: implicit declaration of function ‘malloc’ [-Wimplicit-function-declaration] char *b = (char *)malloc(7000000 * sizeof(char)); ^ user.c:9:23: warning: incompatible implicit declaration of built-in function ‘malloc’ [enabled by default] char *b = (char *)malloc(7000000 * sizeof(char)); ^