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I am Converting a C++ code into C program. I come across a function that takes void draw(char *&a). how to write this function *& in C program. I tried using same *&a but it is showing , (...etc expected. Please help. Thanks

David Heffernan
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karan
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1 Answers1

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There is no pass by reference in C. Therefore you need to change the function declaration to 

void draw(char **a)
haccks
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  • I changed function declaration to void draw(char **a) but its showing expected 'char **' but argument is of type 'char *' – karan Oct 02 '14 at 14:36
  • @karan; Show me how you called the function? – haccks Oct 02 '14 at 14:37
  • void towardDraw(char **a){ draw(a)}; void draw(char **ai){ int a,b,c,d,index=1000,i=1; FILE *f; f=fopen(ai, "r");} – karan Oct 02 '14 at 15:20
  • Well, it should not. – haccks Oct 02 '14 at 15:27
  • yes. but it is not working. – karan Oct 02 '14 at 15:39
  • @karan: You'll need to add `&` to the function call to pass a pointer rather than a reference. So if the C++ does `draw(p)` for some `char * p`, then C will need `draw(&p)`. – Mike Seymour Oct 02 '14 at 17:08
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    @karan: And also dereference the pointer when you use it in that function, to get the `char*` it points to. So in the code you've posted, `fopen(*ai, "r");`. Although, if the function doesn't need to modify the argument, then it should just take it by value, `char *a`, in both languages. – Mike Seymour Oct 02 '14 at 17:10