argv 中的字符串是否可以修改? [英] Are the strings in argv modifiable?

问题描述

我刚刚写了一个小程序，用 C 读取命令行参数，没什么难度.我也在修改它们，例如将参数的第一个字符更改为大写.

I just wrote a small program that reads command line arguments in C, nothing too difficult. I was also modifying them, for example changing the first character of the parameter to uppercase.

我知道您不应该修改字符串文字，因为它会导致未定义的行为，所以我只是想知道 *argv[] 中的字符串是否是您不应该更改的文字.

I know that you shouldn't modify string literals as it can cause undefined behavior, so was just wondering if the strings in the *argv[] are literals that you shouldn't change.

int main(int argc, char *argv[])

推荐答案

来自 C11 标准草案 N1570，§5.1.2.2.1/2:

From the C11 standard draft N1570, §5.1.2.2.1/2:

参数argc和argv以及argv指向的字符串数组应可由程序修改，并保留其最后存储的程序启动和程序终止之间的值.

The parameters argc and argv and the strings pointed to by the argv array shall be modifiable by the program, and retain their last-stored values between program startup and program termination.

它们是可修改的.这意味着它们不是字符串文字.

They are modifiable. That means they are not string literals.

但是要小心:上面的引用仅指指向字符串的指针，不包括argv[argc]1.
来自 C11 标准草案 N1570，§5.1.2.2.1/2(同上)¹:

But be careful: the upper citation only refers to pointers to strings, excluding the obligatory null pointer at argv[argc]¹.
From the C11 standard draft N1570, §5.1.2.2.1/2 (same as above)¹:

argv[argc] 应为空指针

<小时>

注意事项:

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Notes:

• 关于这句话的一些事情:

• Something regarding this sentence:

我知道你不应该修改字符串文字，因为它会导致未定义的行为 [...]

I know that you shouldn't modify string literals as it can cause undefined behavior [...]

可以"吗?它总是如此.未定义的行为包括预期的(好像定义良好的)和意外的行为.

"can"? It does always. Undefined behavior includes expected, as if well-defined, and unexpected behavior.

_{¹ 感谢@black！}

_{¹ Thanks to @black!}

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