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I've seen macros use parentheses to enclose its arguments. Most of these make sense, as in #define sum(a, b) ((a) + (b)) The outer prevents the following: #define sum_bad(a, b) (a) + (b) ...
#4: Post edited
by
alx
·
2023-11-12T11:46:11Z (12 months ago)
When should I parenthesize my macro arguments in C?
- When should I parenthesize macro arguments in C?
#3: Post edited
by
alx
·
2023-11-11T19:22:57Z (12 months ago)
- I've seen macros use parentheses to enclose its arguments. Most of these make sense, as in
- ```c
- #define sum(a, b) ((a) + (b))
- ```
- The outer prevents the following:
- ```c
- #define sum_bad(a, b) (a) + (b)
- s = sum_bad(x, y) * z; // (x) + (y) * z
- ```
- The inner prevents the following:
- ```c
- #define mul_bad(a, b) (a * b)
- m = mul_bad(x, y + z); // (x * y + z)
- ```
- ----
- However, I've seen some parentheses that don't seem justified.
- ```c
- #define foo(a, b) bar((a), (b)) // Why not just `bar(a, b)`
- ```
- ```c
- #define asd(a, b) do \
- {
- int x = (b); // Why not just `= b;`?
- zxc(x);
}- ```
- Is it really necessary to always enclose macro arguments in parentheses, or is it superfluous in some cases?
- I've seen macros use parentheses to enclose its arguments. Most of these make sense, as in
- ```c
- #define sum(a, b) ((a) + (b))
- ```
- The outer prevents the following:
- ```c
- #define sum_bad(a, b) (a) + (b)
- s = sum_bad(x, y) * z; // (x) + (y) * z
- ```
- The inner prevents the following:
- ```c
- #define mul_bad(a, b) (a * b)
- m = mul_bad(x, y + z); // (x * y + z)
- ```
- ----
- However, I've seen some parentheses that don't seem justified.
- ```c
- #define foo(a, b) bar((a), (b)) // Why not just `bar(a, b)`
- ```
- ```c
- #define asd(a, b) do \
- {
- int x = (b); // Why not just `= b;`?
- zxc(x);
- } while (0)
- ```
- Is it really necessary to always enclose macro arguments in parentheses, or is it superfluous in some cases?
#2: Post edited
by
alx
·
2023-11-11T06:05:09Z (12 months ago)
- I've seen macros use parentheses to enclose its arguments. Most of these make sense, as in
- ```c
- #define sum(a, b) ((a) + (b))
- ```
The outer prevent the following:- ```c
- #define sum_bad(a, b) (a) + (b)
- s = sum_bad(x, y) * z; // (x) + (y) * z
- ```
- The inner prevents the following:
- ```c
- #define mul_bad(a, b) (a * b)
- m = mul_bad(x, y + z); // (x * y + z)
- ```
- ----
- However, I've seen some parentheses that don't seem justified.
- ```c
- #define foo(a, b) bar((a), (b)) // Why not just `bar(a, b)`
- ```
- ```c
- #define asd(a, b) do \
- {
- int x = (b); // Why not just `= b;`?
- zxc(x);
- }
- ```
- Is it really necessary to always enclose macro arguments in parentheses, or is it superfluous in some cases?
- I've seen macros use parentheses to enclose its arguments. Most of these make sense, as in
- ```c
- #define sum(a, b) ((a) + (b))
- ```
- The outer prevents the following:
- ```c
- #define sum_bad(a, b) (a) + (b)
- s = sum_bad(x, y) * z; // (x) + (y) * z
- ```
- The inner prevents the following:
- ```c
- #define mul_bad(a, b) (a * b)
- m = mul_bad(x, y + z); // (x * y + z)
- ```
- ----
- However, I've seen some parentheses that don't seem justified.
- ```c
- #define foo(a, b) bar((a), (b)) // Why not just `bar(a, b)`
- ```
- ```c
- #define asd(a, b) do \
- {
- int x = (b); // Why not just `= b;`?
- zxc(x);
- }
- ```
- Is it really necessary to always enclose macro arguments in parentheses, or is it superfluous in some cases?
#1: Initial revision
by
alx
·
2023-11-10T23:47:04Z (12 months ago)
When should I parenthesize my macro arguments in C?
I've seen macros use parentheses to enclose its arguments. Most of these make sense, as in
```c
#define sum(a, b) ((a) + (b))
```
The outer prevent the following:
```c
#define sum_bad(a, b) (a) + (b)
s = sum_bad(x, y) * z; // (x) + (y) * z
```
The inner prevents the following:
```c
#define mul_bad(a, b) (a * b)
m = mul_bad(x, y + z); // (x * y + z)
```
----
However, I've seen some parentheses that don't seem justified.
```c
#define foo(a, b) bar((a), (b)) // Why not just `bar(a, b)`
```
```c
#define asd(a, b) do \
{
int x = (b); // Why not just `= b;`?
zxc(x);
}
```
Is it really necessary to always enclose macro arguments in parentheses, or is it superfluous in some cases?