source: doc/theses/mike_brooks_MMath/programs/bkgd-carray-arrty.c@ 55ba259e

#include <stdio.h>
#include <assert.h>
#include <stdlib.h>

#define SHOW(x, fmt) printf( #x ": " fmt "\n", x )

#ifdef ERRS
#define ERR(...) __VA_ARGS__
#else
#define ERR(...)
#endif

// int main( int argc, const char *argv[] ) {
//     assert(argc == 2);
//     const int n = atoi(argv[1]);
//     assert(0 < n && n < 1000);

//     float a1[42];
//     float a2[n];
//     SHOW(sizeof(a1), "%zd");
//     SHOW(sizeof(a2), "%zd");

// }


        // SHOW(sizeof( a   ), "%zd");
        // SHOW(sizeof(&a   ), "%zd");
        // SHOW(sizeof( a[0]), "%zd");
        // SHOW(sizeof(&a[0]), "%zd");



int main() {
        float ar[10];
        static_assert( sizeof(float) == 4 );    $\C{// floats (array elements) are 4 bytes}$
        static_assert( sizeof(void *) == 8 );   $\C{// pointers are 8 bytes}$
        static_assert( sizeof(ar) == 40 );              $\C{// array}$
        static_assert( sizeof(&ar) == 8 );              $\C{// pointer to array}$
        static_assert( sizeof(ar[0]) == 4 );    $\C{// first element}$
        static_assert( sizeof(&(ar[0])) == 8 ); $\C{// pointer to first element}$

        typeof(&ar) x = &ar;                                    $\C{// x is pointer to array}$
        typeof(&(ar[0])) y = &ar[0];                    $\C{// y is pointer to first element}$
        @x = y;@                                                                $\C{// ill-typed}$
        @y = x;@                                                                $\C{// ill-typed}$
        static_assert( sizeof(typeof(ar)) == 40 ); $\C{// array}$
        static_assert( sizeof(typeof(&ar)) == 8 );      $\C{// pointer to array}$
        static_assert( sizeof(typeof(ar[0])) == 4 ); $\C{// first element}$
        static_assert( sizeof(typeof(&(ar[0]))) == 8 ); $\C{// pointer to first element}$

        void f( float (*pa)[10] ) {
                static_assert( sizeof( *pa ) == 40 ); $\C{// array}$
                static_assert( sizeof( pa ) == 8 );     $\C{// pointer to array}$
                static_assert( sizeof( (*pa)[0] ) == 4 ); $\C{// first element}$
                static_assert( sizeof(&((*pa)[0])) == 8 ); $\C{// pointer to first element}$
        }
        f( &ar );

        float fs[] = {3.14, 1.77};
        char cs[] = "hello";
        static_assert( sizeof(fs) == 2 * sizeof(float) );
        static_assert( sizeof(cs) == 6 * sizeof(char) );  $\C{// 5 letters + 1 null terminator}$

        float fm[][2] = { {3.14, 1.77}, {12.4, 0.01}, {7.8, 1.23} };  $\C{// brackets define structuring}$
        char cm[][sizeof("hello")] = { "hello", "hello", "hello" };
        static_assert( sizeof(fm) == 3 * 2 * sizeof(float) );
        static_assert( sizeof(cm) == 3 * 6 * sizeof(char) );
}

void syntaxReferenceCheck(void) {
        // $\rightarrow$ & (base element)
        //     & @float@ 
        //     & @float x;@ 
        //     & @[ float ]@
        //     & @[ float ]@
        float x0;

        // $\rightarrow$ & pointer
        //     & @float *@ 
        //     & @float * x;@ 
        //     & @[ * float ]@
        //     & @[ * float ]@
        float * x1;

        // $\rightarrow$ & array 
        //     & @float[10]@ 
        //     & @float x[10];@ 
        //     & @[ [10] float ]@
        //     & @[ array(float, 10) ]@
        float x2[10];

        typeof(float[10]) x2b;

        // & array of pointers
        //     & @(float*)[10]@
        //     & @float *x[10];@
        //     & @[ [10] * float ]@
        //     & @[ array(*float, 10) ]@
        float *x3[10];
//    (float *)x3a[10];  NO

        // $\rightarrow$ & pointer to array
        //     & @float(*)[10]@
        //     & @float (*x)[10];@
        //     & @[ * [10] float ]@
        //     & @[ * array(float, 10) ]@
        float (*x4)[10];

        // & pointer to array
        //     & @(float*)(*)[10]@
        //     & @float *(*x)[10];@
        //     & @[ * [10] * float ]@
        //     & @[ * array(*float, 10) ]@
        float *(*x5)[10];
        x5 =     (float*(*)[10]) x4;
//    x5 =     (float(*)[10]) x4;  // wrong target type; meta test suggesting above cast uses correct type

        // [here]
        // const

        // [later]
        // static
        // star as dimension
        // under pointer decay:                int p1[const 3]  being  int const *p1

        const float * y1;
        float const * y2;
        float * const y3;

        y1 = 0;
        y2 = 0;
        // y3 = 0; // bad

        // *y1 = 3.14; // bad
        // *y2 = 3.14; // bad
        *y3 = 3.14;

        const float z1 = 1.414;
        float const z2 = 1.414;

        // z1 = 3.14; // bad
        // z2 = 3.14; // bad


}

#define T float
void stx2() { const T x[10];
//            x[5] = 3.14; // bad
                        }
void stx3() { T const x[10];
//            x[5] = 3.14; // bad
                        }

// Local Variables: //
// compile-command: "sed -f sedcmd bkgd-carray-arrty.c | gcc-11 -Wall -Wextra -x c -" //
// End: //