Editing C syntax (section)

====Array parameters====
Function parameters of array type may at first glance appear to be an exception to C's pass-by-value rule. The following program will print 2, not 1:
<syntaxhighlight lang=C>
#include <stdio.h>

void setArray(int array[], int index, int value)
{
    array[index] = value;
}

int main(void)
{
    int a[1] = {1};
    setArray(a, 0, 2);
    printf ("a[0]=%d\n", a[0]);
    return 0;
}
</syntaxhighlight>

However, there is a different reason for this behavior. In fact, a function parameter declared with an array type is treated like one declared to be a pointer. That is, the preceding declaration of {{code|setArray}} is equivalent to the following:
<syntaxhighlight lang=C>
void setArray(int *array, int index, int value)
</syntaxhighlight>

At the same time, C rules for the use of arrays in expressions cause the value of {{code|a}} in the call to {{code|setArray}} to be converted to a pointer to the first element of array {{code|a}}. Thus, in fact this is still an example of pass-by-value, with the caveat that it is the address of the first element of the array being passed by value, not the contents of the array.

Since C99, the programmer can specify that a function takes an array of a certain size by using the keyword {{code|static}}. In <code>void setArray(int array[static 4], int index, int value)</code> the first parameter must be a pointer to the first element of an array of length at least 4. It is also possible to add qualifiers (<code>const</code>, <code>volatile</code> and <code>restrict</code>) to the pointer type that the array is converted to by putting them between the brackets.