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Q&A Is omitting braces for single statements bad practice?

While there are already good answers, i want to give yet another reason to always use {}: Macros. Lets consider this code: #include <stdio.h> #define FOO(n) puts(n[1]); puts(n[0]); in...

posted 1y ago by H_H‭ · edited 1y ago by H_H‭

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#2: Post edited by

H_H‭ · 2023-08-21T13:28:30Z (about 1 year ago)

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While there are already good answers, i want to give yet another reason to always use `{}`: Macros.
Lets consider this code:
```
#include <stdio.h>
#define FOO(n) puts(n[1]); puts(n[0]);
int main(int argc, char **argv)
{
if(argc>1)
FOO(argv);
}
```
~~You may expect that the Macro `FOO` is only executed when `argc>1`, but no, the code gets expanded to:~~
```
...
if(argc>1)
puts(n[1]); puts(n[0]);
....
```
Which is the same as:
```
...
if(argc>1)
puts(n[1]);
puts(n[0]);
....
```
Which probably wasn't the intention. While the macro `FOO` is written in a bad way (because it allows this error), this error could still have been prevented by using `{}` for the `if`.

While there are already good answers, i want to give yet another reason to always use `{}`: Macros.
Lets consider this code:
```
#include <stdio.h>
#define FOO(n) puts(n[1]); puts(n[0]);
int main(int argc, char **argv)
{
if(argc>1)
FOO(argv);
}
```
You may expect that the code inside the macro `FOO` is only executed when `argc>1`, but no, some of the code is always executed. The code gets expanded to:
```
...
if(argc>1)
puts(n[1]); puts(n[0]);
....
```
Which is the same as:
```
...
if(argc>1)
puts(n[1]);
puts(n[0]);
....
```
Which probably wasn't the intention. While the macro `FOO` is written in a bad way (because it allows this error), this error could still have been prevented by using `{}` for the `if`.

#1: Initial revision by

H_H‭ · 2023-08-21T13:25:22Z (about 1 year ago)

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While there are already good answers, i want to give yet another reason to always use `{}`: Macros.

Lets consider this code:

```
#include <stdio.h>

#define FOO(n) puts(n[1]); puts(n[0]);

int main(int argc, char **argv)
{
  if(argc>1)
    FOO(argv);
}

```

You may expect that the Macro `FOO` is only executed when `argc>1`, but no, the code gets expanded to:
```
...
  if(argc>1)
    puts(n[1]); puts(n[0]);
....
```
Which is the same as:
```
...
  if(argc>1)
    puts(n[1]); 
  puts(n[0]);
....
```

Which probably wasn't the intention. While the macro `FOO` is written in a bad way (because it allows this error), this error could still have been prevented by using `{}` for the `if`.

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