13
Apr
What is allowed in C, but not in C++?
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Following are few differece in C and C++. Few of these are allowed in
C++, but with a different meaning; while some are illegal.
1. sizeof (’1′) == sizeof (int) in C; but it is sizeof (char) in C++.
2. You generally should NOT use *alloc()/free() in C++; but they are the
only such functions in C. Use new and delete combination, instead.
3. Functions need not be prototyped in C; but, it’s a must in C++.
Peter Nilsson says:
"C99 changed from C90 in that named functions must be _declared_ prior
to usage, but there is still no requirement that the function be
prototyped. [The exception being variadic functions like printf,
which have always required prototypes in standard C.]"
4. struct a {
struct b {
int a;
};
};
struct b b; /* allowed in C; but, not in C++ */
5. const int b = 1; /* allowed in C and C++ */
const int a; /* allowed in C, but not in C++ */
6. Global variables can be defined more than once in C, not in C++.
int a; /* both in C and C++ */
int a = 10; /* legal in C; illegal in C++ */
7. const a; /* allowed in C; illegal in C++ */
This is equivalent to const int a; in C.
8. char s[7] = "vijoeyz"; /* error in C++, but allowed in C */
9. K&R style function definitions are not allowed in C++. Example:
void mango ( a )
int a;
{ … }
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Related Blog Items - char** from static variables
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Related Blog Items
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- Differences between new, malloc; delete, free
- Size of an empty class
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