当我越过第 22 行时，我仍然可以看到来自 y 的奇怪值，这让我认为 y 没有正确初始化。但是当我再走 2 步到达返回线时，数字就正确了。
这里发生了什么？我试图关闭优化，但它不起作用
1#include <iostream>
2#include <cstring>
3#include <cmath>
4using namespace std;
5
6const int MD = 10;
7struct BigNumber{
8 int digits[MD];
15 }
16
17 BigNumber(){
18 memset( digits, 0, sizeof(digits));
19 }
20
***21 BigNumber test(){
22 BigNumber p,c,y;// on this line , y is seen as garbage
23 p=c;// on this line , y is seen as garbage
24 c=y;
25 //y=p;
26 return y; // on this line, y returned to correct number
27=>}***
28
29
30 friend ostream& operator<<(ostream& out, const BigNumber& b );
31};
32
33ostream& operator<<(ostream& out, const BigNumber& b){
34 for( int i=MD-1; i>=0; i-- ){
35 out << b.digits[i];
36 }
37 return out;
38}
39
40
41
42int main( ){
43 BigNumber l("4");
44 BigNumber r;
45 BigNumber p,c,y;
46
47 r=l.test();
48 cout << r << endl;
49 cout << l.test() << endl;
50 return 0;
51}
28
(gdb) p p
$8 = {digits = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}
(gdb) p c
$9 = {digits = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}
(gdb) p y
$10 = {digits = {1171907, 1235664, -1208027616, 1, 1, 0, 1, 134513360, 134520860, 0}}
(gdb) n
(gdb) n
(gdb) p y
$11 = {digits = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}