Why would you make a struct without typedef?

Question

Since I cut my teeth on code with OO, I’m biased toward using structs as classes without methods. However, there’s probably a good reason that typedef isn’t the default behavior of struct. What is it?

• amon: What do you mean by "structs as classes without methods"? And what has a typedef got to do with that?
• Caleth: @amon struct foo { ... }; vs typedef struct { ... } foo_t;
• amon: @Caleth yes but what does that typedef have to do with OOP?
• BobDalgleish: What does the language C have to do with object-oriented programming?
• Ben Cottrell: @JohnnyApplesauce it makes no difference. struct objects are just as object-like regardless of whether you use the typedef keyword

Answer 1

C doesn't offer custom namespaces as C++ does, but it's untrue that C doesn't have namespaces at all. Functions and structures are in different namespaces:

#include <stdio.h>
void Test ( ) {
 printf("Hello World\n");
}
struct Test {
 int field1;
 int field2;
};
int main ( ) {
 struct Test t = { 0, 1 };
 Test();
 return 0;
}

When you typedef, you are forcing structures into the same namespace as functions:

#include <stdio.h>
typedef struct {
 int field1;
 int field2;
} Test;
void Test ( ) {
 printf("Hello World\n");
}
int main ( ) {
 Test t = { 0, 1 };
 Test();
 return 0;
}

results in

main.c:8:6: error: ‘Test’ redeclared as different kind of symbol
 void Test ( ) {
 ^~~~
main.c:6:3: note: previous declaration of ‘Test’ was here
 } Test;

• JohnnyApplesauce: Very enlightening!