Hi All.. I cannot find the mistake in this code.
PS: I don't want to change my function to "int create_vect (void)". I'd like to know why it doesn't work in THIS wayCode:#include <stdio.h> #include <stdlib.h> void create_vect (int** v) { *v = (int *) malloc(2 * sizeof(int)); *v[0] = *v[1] = 85; } int main() { int* v; create_vect(&v); printf("%d %d\n", v[0], v[1]); //it prints "85 0". Why? It should be "85 85" return 0; }
Thank you in advance !!!!
Because of operator precedence, you need to change this:
to this:Code:*v[0] = *v[1] = 85;
[] has higher precedence than *, so an expression like *v[0] evaluates to *(v[0]). But if you think about it, you need (*v)[0]. To get that, you add the parentheses.Code:(*v)[0] = (*v)[1] = 85;
Here's an operator precedence table in case you're interested (it's kind of technical): http://cppreference.com/operator_precedence.html
dwk
Seek and ye shall find. quaere et invenies.
"Simplicity does not precede complexity, but follows it." -- Alan Perlis
"Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
"The only real mistake is the one from which we learn nothing." -- John Powell
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Oh my god !!!
Really Fast Reply
I'm so stupid.. I didn't know about that precedence
Anyway, Thank you very muchNow it woks !
I've del.icio.used your website
Yes, you tend to get very fast replies on this board, depending on when you post the question. Sometimes you could get three people answering your question within as many minutes.
I don't update mny website very often . . . for a while there I uploaded codeform version 1.2.0 to it at least twice a week, but now it doesn't get changed very much.
dwk
Seek and ye shall find. quaere et invenies.
"Simplicity does not precede complexity, but follows it." -- Alan Perlis
"Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
"The only real mistake is the one from which we learn nothing." -- John Powell
Other boards: DaniWeb, TPS
Unofficial Wiki FAQ: cpwiki.sf.net
My website: http://dwks.theprogrammingsite.com/
Projects: codeform, xuni, atlantis, nort, etc.
a fast and easy c reference guide is what i needed
nice work
Don't cast the return value of malloc(), there is no need.
