静态C字符串分配问题 [英] Static C string allocation question

问题描述

考虑以下code：

char* str = "Hello World";
memcpy(str, "Copy\0", 5);

在memcpy的过程中出现分段错误。但是，使用此code：

A segmentation fault occurs during the memcpy. However, using this code:

char str[12];
memcpy(str, "Hello World\0", 12);
memcpy(str, "Copy\0", 5);

该程序不会产生分段错误。

The program does not produce a segmentation fault.

问题是否从堆栈与数据部分的分配内存出现？

Does the problem arise from allocating the memory on the stack versus the data section?

推荐答案

当你使用一个字符串字面GCC的价值被放置在只读存储器，不能修改。试图修改它会导致不确定的行为。通常当你尝试这样做，你将获得在Linux分割故障。

When you use a string literal in gcc the value is placed in read-only memory and cannot be modified. Trying to modify it leads to undefined behaviour. Usually you will get a segmentation fault on Linux when you try to do this.

第二个例子的作品，因为你没有修改字符串，您正在修改存储在变量的副本是不是只读的。

The second example works because you aren't modifying the string literal, you are modifying a copy of it that is stored in variable that is not read-only.

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