extend.c

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

typedef unsigned char *byte_pointer;

void show_bytes(byte_pointer start, int len) {
    int i;
    for (i = 0; i < len; i++)
	printf(" %.2x", start[i]);
    printf("\n");
}

void test() {
    /* $begin extend */
    short sx = -12345;       /* -12345 */
    unsigned short usx = sx; /*  53191 */
    int   x = sx;            /* -12345 */
    unsigned  ux = usx;      /*  53191 */

    printf("sx  = %d:\t", sx);
    show_bytes((byte_pointer) &sx, sizeof(short));
    printf("usx = %u:\t", usx);
    show_bytes((byte_pointer) &usx, sizeof(unsigned short));
    printf("x   = %d:\t", x);
    show_bytes((byte_pointer) &x, sizeof(int));
    printf("ux  = %u:\t", ux);
    show_bytes((byte_pointer) &ux, sizeof(unsigned));
    /* $end extend */
}

void test2() {
    /* $begin extenduy */
    short sx = -12345;       /* -12345   */
    unsigned  uy = sx;       /* Mystery! */

    printf("uy  = %u:\t", uy);
    show_bytes((byte_pointer) &uy, sizeof(unsigned));
    /* $end extenduy */
}


int main(int argc, char *argv[]) {
    test();
    test2();
    return 0;
}