Error in declaration in Global Variable

[rejowan]

Why global variable-value declaration has error before the main function "int a; a=10;" ??

#include <iostream>
using namespace std;

int a;
a=10;

int main(){
cout<<a;
}

Why the "a=10;" is error?Again:

#include <iostream>
using namespace std;

int a=10;

int main(){
cout<<a;
}

has no error? And also:

#include <iostream>
using namespace std;

int main(){
int a;
a=10;
cout<<a;
}

is correct?

Please explain.

[CptJY]

You cannot do an assignation or call a function outside a function.

[rejowan]

More details please.

[AbstractionAnon]

First snippet line 5 is a stand-alone assignment statement. Executable statements are not allowed outside of functions.

Second snippet line 4 is an initialization of a global, which is allowed.

Third snippet - everything is within a function, which is fine.

[rejowan]

Thanks.