又遇到的一些

#include <stdio.h>
#include <stddef.h>
int main()
{
    /*
    unsigned int u;
     int k = -1;
    if(u>k){
        printf(">-1\n");
    }
    else if(u == k)
    {
        printf("=-1\n");
    }
    else{
        printf("<-1\n");
    }
    */
/*
    unsigned char uc = -1;
    signed char sc = -1;
    char c = -1;
    int i =uc,j = sc,k = c;
    printf("%d,%d,%d\n",i,j,k);*/
/*
    
    void *generic_ptr;
    int *int_ptr;
    char *char_ptr;
    generic_ptr = int_ptr;
    int_ptr = generic_ptr;
    int_ptr = char_ptr;*/
  
    int *p = NULL ;
    int a = 10;
    p = &a;    
    printf("%d,%x,%d\n",p,p,*p);
    p++;
    printf("%d\n",p,*p);
    printf("%d,%d\n",(a+1,a),a);//这里执行顺序是怎样的
    
    int arr[]={6,7,8,9,10};
    int *ptr=arr;
    printf( "%d,%d,%d ",*ptr,*(++ptr),*(ptr--));//同上，从论坛中看到的例子
    return 0;
}

这些我都作了实验，实际中最后的printf执行顺序问题的确跟具体的编译器有关，有的是从左向右，有的是从右向左；