How can we initialize a structure with an array (using its variable)?
This version works well:
MyStruct test = {"hello", 2009};
But this version is bugged:
char str[] = "hello";
MyStruct test = {str, 2009};
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It would help if you posted the definition of 'typedef struct MyStruct { ... } MyStruct;'.Jonathan Leffler– Jonathan Leffler2009-11-19 22:59:46 +00:00Commented Nov 19, 2009 at 22:59
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2 Answers
You cannot assign arrays in C, so unfortunately there's no way to do that directly. You may use strcpy to copy the data, though.
typedef struct {
char name[20];
int year;
} MyStruct;
int main() {
MyStruct a = { "hello", 2009 }; // works
char s[] = "hello";
MyStruct b = { "", 2009 }; // use dummy value
strcpy(b.name, s);
return 0;
}
4 Comments
asveikau
I would use strlcpy() or strncpy_s() if available. strncpy() as a semi-last resort. strcpy() only if you know that it won't overflow and feel like making god cry.
Jonathan Leffler
You can do array assignments as part of a structure assignment:
struct a { int b[10]; } a, b = { 0 }; a = b;
quinmars
@asveikau, better use snprintf() instead of strncpy(), this will ensure that your string is nul-terminated.
The definition of MyStruct should contain a first member of type char const *.
1 Comment
Jonathan Leffler
Or, slightly more expansively, if the definition of MyStruct contained a char pointer (or, better, a 'const char *'), then the second initializer would work correctly.