作为函数参数的char *args[]与char **argv有何区别？是否等价？

Great question! Let's cut through the confusion here—you're absolutely right to question the common explanations floating around.

First, let's address the core point: when used as function parameters, char *argv[] and char **argv are completely equivalent. The popular claim that "char *argv[] is an array of pointers, char **argv is a pointer to a pointer" is only true for variable declarations outside function parameters. Inside a function's parameter list, array types undergo what's called "array decay"—the compiler automatically converts the array type to a pointer to its first element.

So when you write:

int main(int argc, char *argv[]) { ... }

The compiler treats argv exactly the same as if you had written:

int main(int argc, char **argv) { ... }

Your observation about being able to use argv as an lvalue (on the left side of an assignment) is perfect proof of this. A true array variable cannot be assigned to—try this in main, and you'll get a compiler error:

int main() {
    char *real_array[] = {"a", "b", NULL};
    char *another_array[] = {"x", "y", NULL};
    real_array = another_array; // ❌ Compile error: array type is not assignable
    return 0;
}

But do the same inside a function where argv is declared as char *argv[], and it works perfectly:

void process_args(char *argv[]) {
    char *new_args[] = {"hello", "world", NULL};
    argv = new_args; // ✅ Totally legal—argv is a char** pointer here
    printf("%s\n", argv[0]); // Outputs "hello"
}

Why does this happen? Because function parameters can't be arrays. The syntax char *argv[] is just syntactic sugar that makes the code more readable (it hints that we're dealing with an array of strings), but under the hood, it's a pointer to a pointer.

To sum up:

• For variable declarations (not function parameters), char *arr[] is an array of pointers, and char **ptr is a pointer to a pointer—these are distinct types.
• For function parameters, char *argv[] is converted to char **argv by the compiler. They are identical in behavior, memory representation, and what you can do with them.

内容的提问来源于stack exchange，提问作者ynn