程序代码：

#include<stdio.h>
int main(){
    //int a(3003);
    int a = 3003; 
    printf("%d",a);
    return 0;
}

程序代码：

root@localhost:~# cat a.c 
#include<stdio.h>
int main(){
    int a(3003);
    // int a = 3003; 
    printf("%d",a);
    return 0;
}
root@localhost:~# gcc a.c 
a.c: In function 'main':
a.c:3:11: error: expected declaration specifiers or '...' before numeric constant
     int a(3003);
           ^
a.c:5:17: error: 'a' undeclared (first use in this function)
     printf("%d",a);
                 ^
a.c:5:17: note: each undeclared identifier is reported only once for each function it appears in
root@localhost:~#