is char** val the same as char* val[ ]

[otengkwaku]

is char** val the same as char* val[ ] when is the formal ( char** val) used

[deceptikon]

is char** val the same as char* val[ ]

Only as formal parameters in a function definition. Otherwise, they're not. I'm assuming we're talking about parameters for the answer to your next question.

when is the formal (char** val) used

I'll use the array notation when I'm absolutely sure that the function is intended to work with an array or simulated array. I prefer to use pointer notation when the object is known to not be an array or whether it's an array is unknown.

[otengkwaku]

so if i get you, they are all array notation but char** val is implicite and
char* val[] is explicite
because i just noticed that using int main (int argv, char** argc) worked the same way as int main (int argv, char* argc[])

[deceptikon]

they are all array notation but char** val is implicite and char* val[] is explicite

It's the other way around. They are all pointers, and the [] option is syntactic sugar to highlight the intention that the parameter is an array. But also note that this equivalence only applies to the first dimension of a the array notation. All subsequent dimensions require a size and represent array types. Consider this:

int main()
{
    int a[2][4];

    foo(a);
}

foo() must be declared in one of two ways:

void foo(int a[][4]);  /* First dimension decays into a pointer */
void foo(int (*a)[4]); /* Explicitly stating the first dimension as a pointer */

It's a common misconception that the double pointer type corresponds to a 2D array, which is false:

void foo(int **a); /* Fails to compile */

[otengkwaku]

ok ok ok thanks a lot
question solved