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2 questions on C

 
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kitesan
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PostPosted: Sat Jan 28, 2017 9:27 am    Post subject: 2 questions on C Reply with quote
1)Why declaring a pointer to a string (char *Ptr = "literal") makes that string const? and (char str[] = "literal") doesnt?

2) For a C programmer, is it necessary to remember stdlib functions relating string management?
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atom0s
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PostPosted: Sat Jan 28, 2017 2:24 pm    Post subject: This post has 2 review(s) Reply with quote
1. You can find the answer within the C standard here:
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf

Look at section 6.4.5 for string literals. The main point you will want to read would be:
Code:
The contents of the arrays are modifiable. On the other hand, the declaration
char *p = "abc";
defines p with type ‘‘pointer to char’’ and initializes it to point to an object with type ‘‘array of char’’
with length 4 whose elements are initialized with a character string literal. If an attempt is made to use p to
modify the contents of the array, the behavior is undefined.


Using a pointed literal is considered undefined behavior which leaves it as an assumed const.

2. I'm not quite sure I understand your question. Are you asking if you need to remember them without having to look them up? There is nothing wrong if referencing the documentation when needed. You are not going to remember every single function in the standard libraries for C or C++. It is better to reference the docs than to guess and write bad code that has issues.
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kitesan
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PostPosted: Sat Jan 28, 2017 2:47 pm    Post subject: Reply with quote
Yeah, you're totally right , and by the way thanks alot for the answer. I'm going to download that pdf as i'll probably need it again
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