I am reading C Programming: A Modern Approach by K.N.King to learn the C programing language and the current chapter tells about functions, and also array parameters. It is explained that one can use constructs like these to express the length of array parameters:
1.
void myfunc(int a, int b, int[a], int[b], int[*]); /* prototype */
void myfunc(int a, int b, int n[a], int m[b], int c[a+b+other_func()]) {
... /* body */
}
2.
void myfunc(int[static 5]); /* prototype */
void myfunc(int a[static 5]) {
... /* body */
}
So the question(s) are:
a. Are the constructs in example 1 purely cosmetic or do they have an effect on the compiler?
b. Is the static
modifier in this context only of cosmetic nature? what exactly does it mean and do?
c. Is it also possible to declare an array parameter like this; and is it as cosmetic as example 1 is?
void myfunc(int[4]);
void myfunc(int a[4]) { ... }
With the help of the length variable, we can obtain the size of the array. Examples: int size = arr[]. length; // length can be used // for int[], double[], String[] // to know the length of the arrays.
length vs length()The length variable is applicable to an array but not for string objects whereas the length() method is applicable for string objects but not for arrays.
One common way of creating an Array with a given length, is to use the Array constructor: const LEN = 3; const arr = new Array(LEN); assert.
A parameter array can be used to pass an array of arguments to a procedure. You don't have to know the number of elements in the array when you define the procedure. You use the ParamArray keyword to denote a parameter array.
The innermost dimension of function array parameters is always rewritten to a pointer, so the values that you give there don't have much importance, unfortunately. This changes for multidimensional arrays: starting from the second dimension these are then used by the compiler to compute things like A[i][j]
.
The static
in that context means that a caller has to provide at least as many elements. Most compilers ignore the value itself. Some recent compilers deduce from it that a null pointer is not allowed as an argument and warn you accordingly, if possible.
Also observe that the prototype may have *
so clearly the value isn't important there. In case of multidimensional arrays the concrete value is the one computed with the expression for the definition.
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