char * argv []如何在c/c ++中工作? [英] how does char* argv[] work in c/c++?

问题描述

我知道它用于从命令行使用参数，但是我没有得到声明.char * argv []?这是否意味着指向char数组的指针，如果是，为什么没有大小呢?如果它不是动态数组，就不必具有大小吗?

I know it is used to use arguments from the command line, I don't get the declaration though. char* argv[]? does it mean a pointer to a char array, if so why no size? don't you have to have a size if it's not a dynamic array?

我做了一些研究，发现有人说它会分解为char ** argv.这种腐烂的东西是如何工作的?

I have done a bit of research and come across people saying it decays to char **argv. how does this decay thing work?

感谢您的帮助-非常抱歉，您是菜鸟xD

Thanks for your help - sorry for being a noob xD

推荐答案

查看 argv 的最好方法是将其作为指向字符/字符串的指针的数组.每个 argv [i] 都指向一个字符，该字符是一个以空字符结尾的字符串的开头.

The best way to look at argv is as an array of pointers to characters/strings. Each argv[i] points to a character which is the start of a null-terminated string.

您传递了 argc 来告诉您数组中有多少个条目，但这在技术上是多余的，因为 argv [argc] == NULL ，所以您有两个检测参数列表结尾的方法.

You are passed argc to tell you how many entries are in the array, but this is technically redundant since argv[argc] == NULL, so you have two ways of detecting the end of the argument list.

衰减事物"是当您将数组传递给函数时，将其视为指向数组第一个元素的指针.

The decay 'thing' is that when you pass an array to a function, it is treated as a pointer to the first element of the array.

因此，如果将 int a [10] 传递给函数，则该值为& a [0] 且为 int * .在函数声明或定义中，可以互换地编写 int * x 或 int x [] .此元素与 argv 之间的唯一区别是元素类型不是 int 而是 char * ，因此 char * argv [] 和 char ** argv 在函数的声明或定义中是等效的.请注意，此等价不适用于局部变量或全局变量. extern char ** v; 和 extern char * a []; 之间存在主要区别.

Thus, if you pass int a[10] to a function, the value is &a[0] and is an int *. In the function declaration or definition, you can write int *x or int x[] interchangeably. The only difference between this and argv is that the element type is not int but char *, so char *argv[] and char **argv are equivalent in the declaration or definition of a function. Note that this equivalence does not apply to either local or global variables. There are major differences between extern char **v; and extern char *a[];.

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