Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
597 views
in Technique[技术] by (71.8m points)

c - dereferencing pointer to integer array

I have a pointer to integer array of 10. What should dereferencing this pointer give me?

Eg:

#include<stdio.h>

main()
{
    int var[10] = {1,2,3,4,5,6,7,8,9,10};
    int (*ptr) [10] = &var;

    printf("value = %u %u
",*ptr,ptr);  //both print 2359104. Shouldn't *ptr print 1?


}
See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Answer

0 votes
by (71.8m points)

What you dereference is a pointer to an array. Thus, dereferencing gives you the array. Passing an array to printf (or to any function) passes the address of the first element.

You tell printf that you pass it an unsigned int (%u), but actually what is passed is an int*. The numbers you see are the addresses of the first element of the array interpreted as an unsigned int.

Of course, this is undefined behavior. If you want to print an address, you have to use %p and pass a void*.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...