[英]Where does this code segfault?
My question, now reduced to a - hopefully - minimal example, is why the following code segfaults. 我的问题,现在简化为 - 希望 - 最小的例子,是以下代码段错误的原因。
It can of course be seen as a duplicate of the proposed question, provided you have found the latter. 如果您找到后者,它当然可以被视为提议问题的副本。 The problem is, I failed to find the question in my initial search and so may many newbies, not knowing the cause of error.
问题是,我在初始搜索中找不到问题,所以可能有很多新手,不知道错误的原因。 I propose this as a duplicate I could have found:
我建议将此作为我可以找到的副本:
Segmentation Fault before main 主要之前的分段故障
but the problem description is very long, so that I believe my minimised and much shorter code might be better for illustrating the problem. 但问题描述很长,所以我相信我的最小化和更短的代码可能更好地说明问题。 In any case, it is a duplicate.
在任何情况下,它都是重复的。 I propose the moderators set this as a duplicate and set a link from the second possible duplicate to the first one.
我建议主持人将其设置为副本,并设置从第二个可能副本到第一个副本的链接。
#include <stdio.h>
/* Parameters */
#define N 3072
#define LDA N
/* Main program */
int main() {
printf( "-----------------------------------------------> Entry main.\n" );
/* Local arrays */
double a[LDA*N];
printf( "-----------------------------------------------> End main.\n" );
return 0;
}
A segfault does not occur when 当发生段错误时不会发生
#define N 3072
is replaced by 被替换为
#define N 5
Neither does a segfault occur when the line 线路时也不会发生段错误
double a[LDA*N];
is omitted. 省略。
I am especially confused by the observation that the segfault occurs without reaching 我特别感到困惑的是,在没有达到的情况下发生了段错误
printf( "-----------------------------------------------> Entry main.\n" );
which I put directly at the beginning of main. 我直接放在主要的开头。
For completeness, I run the code like this: 为了完整性,我运行如下代码:
ludi@ludi-M17xR4:~/Desktop/tests$ g++ -o minicombo.x minicombo.cc && ./minicombo.x
The segfault is likely due to the array definition double a[LDA*N];
segfault可能是由于数组定义
double a[LDA*N];
. 。 This creates a 72MB array with automatic storage duration ("on the stack").
这将创建一个具有自动存储持续时间的72MB阵列(“在堆栈上”)。 You have several alternatives.
你有几种选择。
std::vector<double>
created with the desired size or resize()
member function. resize()
成员函数创建的std::vector<double>
。 std::unique_ptr<double[]>
or new[]/delete[]
. std::unique_ptr<double[]>
或new[]/delete[]
动态分配。 Beware, manual memory management is fraught with peril. static
or global. static
或全局。
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