1 #include <stdio.h> 2 #include <math.h> 3 #include <string.h> 4 int i = 9; 5 void a() 6 { 7 i = 90; 8 printf("%d ", i); 9 } 10 int main(void) 11 { 12 extern int i; 13 a(); 14 printf("%d", i); 15 return 0; 16 }
output : 90 90
output 90 10
extern mark after no revise , no mark availible
原文：https://www.cnblogs.com/constanted/p/14826300.html