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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?

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    What do you mean by "structs as classes without methods"? And what has a typedef got to do with that?
    – amon
    Commented Feb 14, 2020 at 18:52
  • @amon struct foo { ... }; vs typedef struct { ... } foo_t;
    – Caleth
    Commented Feb 14, 2020 at 18:54
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    @Caleth yes but what does that typedef have to do with OOP?
    – amon
    Commented Feb 14, 2020 at 19:35
  • What does the language C have to do with object-oriented programming? Commented Feb 14, 2020 at 19:37
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    @JohnnyApplesauce it makes no difference. struct objects are just as object-like regardless of whether you use the typedef keyword Commented Feb 15, 2020 at 0:46

1 Answer 1

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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;
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