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uint32_t in offset test

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This commit is contained in:
Wolfgang Hottgenroth 2020-12-13 23:04:23 +01:00
parent 64999eaefc
commit e3e6d0bb7b
Signed by: wn
GPG Key ID: E49AF3B9EF6DD469
1 changed files with 10 additions and 2 deletions
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12
offsetTest/test.c
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@ -8,18 +8,20 @@ typedef struct {
uint8_t id; uint8_t id;
char a[16]; char a[16];
uint8_t length; uint8_t length;
uint32_t x;
} t_testObj; } t_testObj;
t_testObj testObj = { .id = 0, .a = "test123", .length = 25 }; t_testObj testObj = { .id = 0, .a = "test123", .length = 25, .x = 123456 };
void printTestObj(t_testObj *testObj) { void printTestObj(t_testObj *testObj) {
printf("testObj: id=%d, a=%s, length=%d\n", testObj->id, testObj->a, testObj->length); printf("testObj: id=%d, a=%s, length=%d, x=%d\n", testObj->id, testObj->a, testObj->length, testObj->x);
} }
int main() { int main() {
printf("id: %ld\n", offsetof(t_testObj, id)); printf("id: %ld\n", offsetof(t_testObj, id));
printf("a: %ld\n", offsetof(t_testObj, a)); printf("a: %ld\n", offsetof(t_testObj, a));
printf("length: %ld\n", offsetof(t_testObj, length)); printf("length: %ld\n", offsetof(t_testObj, length));
printf("x: %ld\n", offsetof(t_testObj, x));
printTestObj(&testObj); printTestObj(&testObj);
@ -40,6 +42,12 @@ int main() {
strcpy((char*)a3, "Wolfgang"); strcpy((char*)a3, "Wolfgang");
printTestObj(&testObj); printTestObj(&testObj);
uint32_t *a4 = (uint32_t*) (((uint8_t*)&testObj) + offsetof(t_testObj, x));
printf("a4: %p\n", a4);
*a4 = 1234567890;
printTestObj(&testObj);
} }