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Is it possible to set default values for some struct member? I tried the following but, it'd cause syntax error:
typedef struct { int flag = 3; } MyStruct; Errors:
$ gcc -o testIt test.c test.c:7: error: expected ‘:’, ‘,’, ‘;’, ‘}’ or ‘__attribute__’ before ‘=’ token test.c: In function ‘main’: test.c:17: error: ‘struct <anonymous>’ has no member named ‘flag’ 
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If a structure variable has static storage, its members are implicitly initialized to zero of the appropriate type. If a structure variable has automatic storage, its members have no default initialization.
Another method to initialize struct members is to declare a variable and then assign each member with its corresponding value separately. Note that char arrays can't be assigned with string, so they need to be copied explicitly with additional functions like memcpy or memmove (see manual).
When we define a struct (or class) type, we can provide a default initialization value for each member as part of the type definition. This process is called non-static member initialization, and the initialization value is called a default member initializer.
The simple answer is yes. It has a default constructor. Note: struct and class are identical (apart from the default state of the accesses specifiers).
Structure is a data type. You don't give values to a data type. You give values to instances/objects of data types.
So no this is not possible in C.
Instead you can write a function which does the initialization for structure instance.
Alternatively, You could do:
struct MyStruct_s { int id; } MyStruct_default = {3}; typedef struct MyStruct_s MyStruct; And then always initialize your new instances as:
MyStruct mInstance = MyStruct_default; If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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