C Pointer to Pointer – Learn C programming in simple and easy steps starting from basic to advanced concepts with examples including C Overview, language . Backend source code. 7. C++ using gcc , C++11, and Valgrind Memcheck. Backend source code. Privacy Policy: By using Python Tutor, your visualized code. As an array, a string in C can be completely twisted, torqued, and abused by using pointers. It’s a much more interesting topic than messing with numeric arrays.

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By continuing to use our f, you agree to our cookie policy. To create this article, 14 people, some anonymous, worked to edit and improve it over time. The distinction doesn’t matter in many cases, but be aware that these are not identical in all architectures. Duncan C 92k 13 Taylor Apr 29 ’11 at By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

This looks a little awkward to some programmers, but it’s perfectly valid. This is not true. Nowadays it can get a bit more complicated, and varies by operating system. Include your email address to get a message when this question is answered. I think the code would be more readable if it’s not in all caps like it’s typed by teenagers on AOL chat from the 90s.

Already answered Not a question Bad question Other. Also this question has been answered for 4. I think that it is used to call members and functions like the equivalent of the. Calling it a caused some confusion for me when I started reading about operator overloading in that other answer, which is not relevant in Orogramlama.


If a function can return NULL, think about whether this is a possibility, and whether that would cause problems later prigramlama your code.

C library function – memcpy()

It’s best to check your pointers against NULL directly, and use 0 in other contexts. You will end up with code like this:.

Test for any value but NULL. It’s common practice to set newly created or newly freed pointers to NULL to make sure you don’t use this unhelpful address by accident. Is this article up to date? Warnings This article is written for C only. The pointer has been assigned a valid value. Post as a guest Name. You will end up with code like poinfer Donald Duck 3, 12 39 Stack Overflow works best with JavaScript enabled.

Here’s an example of the malloc function using the null check if ptr to ensure it only handles pointers with valid values: Sign up using Email and Password. Perhaps more importantly, using NULL makes it obvious that you are working with pointers for other people reading your code.

C library function – memcpy()

Here the to access the values of i and j we can use the variable a and the pointer p as follows: Could I please get an explanation and a code sample? But I am not entirely sure. This keeps your code clean and easy to understand, since you’ll know you’re working with pointers every time you see NULL.

A simple if ptr tests whether ptr is TRUE. Email Required, but never shown. Can you tell us which parts were out of date so we can update them? Jayghosh Wankar 1 7. I am currently learning Prgoramlama by reading a good progdamlama book called “Teach Yourself C in 21 Days” I proramlama already learned Java and C so I am moving at a much faster pace.


Pay attention to functions that could return NULL. After declaring the struct pointer pvar, point it to the address of var. Rich Vogt 43 9. What value does this add? Help answer questions Learn more. Belton The hard way series are bad, the guy says stuff that wasn’t even relevant when he wrote the book and he doesn’t pkinter about good practices. One common mistake is to assume that a newly created pointer has a NULL value. I found this solution on page of Stephen Kochan’s Programming in C.

Write the NULL first to avoid errors optional. We’ll use ptr in this article as the name of the pointer you’re checking. Lukasz Matysiak 2 7. Sign up using Facebook.

C – Pointer to Pointer

Jack k 26 The question was specifically about C, which prohramlama not have classes or reference variables. Thank you for your feedback! Sometimes it’s more convenient to test for inequality instead.

The whole mess of typedef-ing functions with all the extra parentheses would have been avoided as well.