CodePudding user response:
Why don't redefine an errorCodePudding user response:
.c file# define _RTC_APP_C_
# include "PCH. H"
#include
Int BBBB.//here defines the PCH. H and defines why not redefine
Int main ()
{
BBBB=9999;
STD: : cout & lt;
}
.h files
# # ifndef PCH_H
# define PCH_H
Definition in c # ifdef _RTC_APP_C_//in.
# define _RTC_APP_E_
# the else
# define _RTC_APP_E_ extern
# endif
//why this won't be submitted to redefine the wrong
_RTC_APP_E_ int BBBB.
# endif
CodePudding user response:
Because is the externCodePudding user response:
Extern no effectCodePudding user response:
V is the extern but I still in the KEIL definitionCodePudding user response:
Don't have to struggle the compiler is this serious problem some compilers will not tolerate othersIn this just repeat statement you. H file BBBB assignment natural complains, of course, can only say that the compiler is not precise enough tolerance you the small problems
CodePudding user response:
Scope is different, is not the same variable, not wrongCodePudding user response:
The extern is not without effect?CodePudding user response:
You try this code won't be an errorInt BBB.
Int main () {
Int BBB.
{
Int BBB.
}
}
Because c + + variable scope under his recent braces
CodePudding user response:
Combined with extern, that is not defined, but a statement,If global variables are not in the beginning of the file definition, the scope of effective to the end of the file will be restricted to its definition, if before defining point function to reference the global variables, it should be before the reference with keyword extern for the variable "external variable declaration," said the variable is a variable defined external, with this statement, can from the "statement", legally use the external variables