In our Node JS application, prettier reformats this:
if (a == 4) { return 34; }
if (b == 4) { return 36; }
into this:
if (a == 4) {
return 34;
}
if (b == 4) {
return 36;
}
Which makes sense as a default behavior, however we have a strong preference for one liners especially when the if statement is short. Currently our .prettierrc is:
{
"tabWidth": 4,
"useTabs": false,
"singleQuote": true,
"arrowParens": "avoid",
"semi": true,
"trailingComma": "none",
"printWidth": 9999
}
Is there anyway to modify this file to keep short if-statements on one line? We could remove the curly braces but then eslist is unhappy and we do not want to change the eslist curly rule as we do prefer keeping the { } brackets.
I don't think prettier supports that. After all, prettier is an opinionated formatter.
Copied from the docs 🙂:
Prettier is not a kitchen-sink code formatter that attempts to print your code in any way you wish. It is opinionated.
Related
I am copying code of file 1 to file 2 , but i want the code in file 2 to look adjusted with indentation like this: at the beginning indentation=0, every curly bracket opened increases the depth of indentation, every curly bracket closed reduces the indentation 4 spaces for example. I need help in fixing this to work
char preCh;
int depth=0;
int tab = 3;
int d = 0;
int pos = 0;
file1.get(ch);
while(!file1.eof())
{
if(ch=='{')
{
d++;
}
if(ch=='}'){
d--;
}
depth = tab * d;
if(preCh == '{' && ch=='\n'){
file2.put(ch);
for (int i = 0; i <= depth; i++)
{
file2.put(' ');
}
}
else
file2.put(ch);
preCh = ch;
ch = file1.get();
}
}
result must be indented like in code editors:
int main(){
if(a>0)
{
something();
}
}
Maybe, unexpectedly for you, there is no easy answer to your question.
And because of that, your code will never work.
First and most important, you need to understand and define indentation styles. Please see here in Wikipedia. Even in your given mini example, you are mixing Allman and K&R. So, first you must be clear, what to use.
Then, you must be aware that brackets may appear in quotes, double quotes, C-Comments, C++ comments and even worse, multi line comments (and #if or #idefs). This will make life really hard.
And, for the closing brackets, and for example Allman style, you will know the needed indentation only after you printed already the "indentation spaces". So you need to work line oriented or use a line buffers, before you print a complete line.
Example:
}
In this one simple line, you will read the '}' character, after you have already printed the spaces. This will always lead to wrong (too far right) indentation.
The logic for only this case would be complicated. Ant then assume statements like
if (x ==5) { y = 3; } } } }
So, unfortunately I cannot give you an easy solution.
A parser would be needed, or I simply recommend any kinde of beautifier or pretty printer
I don't quite understand the meaning of else if statements.
why not just to continue with the if statements in case one is false?
it works the same.
example with if only that will work the same with else if:
function testSize(num) {
if (num < 5){
return "Tiny";
}
if (num < 10){
return "small";
}
return "Change Me";
}
testSize(7);
In your actual code you specify a return statement in the code associated to the if statement.
Suppose you don't specify a return statement or suppose today you specify a return statement but tomorrow you remove it to do a common return at the end of the method.
This code will test each condition even if the first one is true :
if (num < 5){
// do something
}
if (num < 10){
// do something
}
This code will not test the next condition if the first one is true :
if (num < 5){
// do something
}
else if (num < 10){
// do something
}
These two ways of doing have two distinct meanings.
When you have a series of if statements, you expect that more than one condition may be true.
When you have a series of if-else-if statements, you expect to have not more than one condition true.
Using the first form (a series of if) while functionally you expect to have not more than one condition true is misleading.
Besides, if the code is modified and you add a condition that is both true for two if statements while you don't want have this case, it would create an issue.
Your code is only showing your belief. What would happen in the example below?
function testSize(num) {
if (num < 5){
x = 1;
}
if (num < 10){
x = 2;
}
result = complex calculations;
}
function testSize2(num) {
if (num < 5){
x = 1;
} else if (num < 10){
x = 2;
}
return x * 2;
}
testSize(4); // result is 4
testSize2(4); // result is 2
x may also be involved in more calculations
if(condition) {...}
if(condition) {...}
if(condition) {...}
In above code, even if the first or second condition is true, third condition have to be checked.
if(condition) {}
else if(condition){}
else if(condition){}
Here if first condition is true, next two will not be checked. So, it saves time and is more readable logically.
A one way if statement takes an action if the specified condition is true.If the condition is false, nothing is done. But what if you want to take alternative actions when the conditions is false ? You can use a two-way if-else statement. The action that a two-way if-else statements specifies differ based on whether the condition is true or false.
Well, there is a bit different from this two statement.Consider the follow samples
if(a > 0) {
...
}
if( a == 0) {
...
}
if(a < 0) {
...
}
and
if(a > 0) {
...
}
else if( a == 0) {
...
}
else if(a < 0) {
...
}
when a is zero the last else if statement will not be execute while if need to compare third time.If a equals to 10, else if could be execute once while if is third.From this else if statement could be execute less and let your program a bit fast.
else if should be used when there are multiple conditions and you want only one of them to be executed, for instance:
if(num<3){ console.log('less than 3') }
else if(num<2){ console.log('less than 2')
If you use multiple if statements instead of using else if, it will be true for both the conditions if num = 1, and therefore it will print both the statements.
Multiple if statements are used when you want to run the code inside all those if statements whose conditions are true.
In your case it doesn't make a difference because the function will stop and return at the very first return statement it encounters. But let's say, the blocks' orders are interchanged, then your function will never return 'tiny' even if num = (anything less than 5).
I hope that helps!
If all your if branches terminate the function (e.g., but returning a value of throwing an exception), you're right, and you really don't need an else statement (although some coding standards might recommend it).
However, if the if branches don't terminate the function, you'd have to use an else or else if clause to prevent multiple blocks from being executed. Assume, e.g., you want to log a message to the console instead of returning it:
if (num < 5) {
console.log("Tiny");
} else if (num < 10) {
console.log("small");
} else {
console.log("Change Me");
}
I have a condition like the following where I just want to have the second bool be the trigger for a single time, since this condition is invoked relatively often I don't like the idea of doing the assignment of it being false every time the condition is true so, I tried to take advantage of the order of logical AND and OR and the post increment operator. But it appears to work don't do what I expected it to do. So is there a way to make a post state switch for this line?
where firstTitleNotSet is:
bool firstTitleNotSet;
if (titleChangedSinceLastGet() || (p_firstTitleNotSet && p_firstTitleNotSet++))
The idea is that the first part is the primary trigger and the second is the trigger that only has to trigger the first time.
While I easily could do
if (titleChangedSinceLastGet() || p_firstTitleNotSet)
{
firstTitleNotSet = false;
//...
}
I don't like this as it is reassigning false when ever the conditional block is invoked.
So is there some way of "post change" the value of a bool from true to false? I know that this would work the other way around but this would negate the advantage of the method most time being the true trigger and therefor skipping the following check.
Note: The reasons for me making such considerations isntead of just taking the second case is, that this block will be called frequently so I'm looking to optimize its consumed runtime.
Well, you could do something like:
if (titleChangedSinceLastGet() ||
(p_firstTitleNotSet ? ((p_firstTitleNotSet=false), true):false))
An alternative syntax would be:
if (titleChangedSinceLastGet() ||
(p_firstTitleNotSet && ((p_firstTitleNotSet=false), true)))
Either one looks somewhat ugly. Note, however, that this is NOT the same as your other alternative:
if (titleChangedSinceLastGet() || p_firstTitleNotSet)
{
p_firstTitleNotSet = false;
//...
}
With your proposed alternative, pontificate the fact that p_firstTitleNotSet gets reset to false no matter what, even if the conditional was entered because titleChangedSinceLastGet().
A more readable way than the assignment inside a ternary operator inside an or inside an if would be just moving the operations to their own statements:
bool needsUpdate = titleChangedSinceLastGet();
if(!needsUpdate && firstTitleSet)
{
needsUpdate = true;
firstTitleSet = false;
}
if(needsUpdate)
{
//...
}
This is likely to produce very similar assembly than the less readable alternative proposed since ternary operators are mostly just syntactic sugar around if statements.
To demonstrate this I gave GCC Explorer the following code:
extern bool first;
bool changed();
int f1()
{
if (changed() ||
(first ? ((first=false), true):false))
return 1;
return 0;
}
int f2()
{
bool b = changed();
if(!b && first)
{
b = true;
first = false;
}
return b;
}
and the generated assembly had only small differences in the generated assembly after optimizations. Certainly have a look for yourself.
I maintain, however, that this is highly unlikely to make a noticeable difference in performance and that this is more for interest's sake.
In my opinion:
if(titleChangedSinceLastUpdate() || firstTitleSet)
{
firstTitleSet = false;
//...
}
is an (at least) equally good option.
You can compare the assembly of the above functions with this one to compare further.
bool f3()
{
if(changed() || first)
{
first = false;
return true;
}
return false;
}
In this kind of situation, I usually write:
bool firstTitleNotSet = true;
if (titleChangedSinceLastGet() || firstTitleNotSet)
{
if (firstTileNotSet) firstTitleNotSet = false;
//...
}
That second comparison will likely be optimized by the compiler.
But if you have a preference for a post-increment operator:
int iterationCount = 0;
if (titleChangedSinceLastGet() || iterationCount++ != 0)
{
//...
}
Note that this will be a problem if iterationCount overflows, but the same is true of the bool firstTitleNotSet that you were post-incrementing.
In terms of code readability and maintainability, I would recommend the former. If the logic of your code is sound, you can probably rely on the compiler to do a very good job optimizing it, even if it looks inelegant to you.
That should work:
int firstTitleSet = 0;
if (titleChangedSinceLastGet() || (!firstTitleSet++))
If you wish to avoid overflow you can do:
int b = 1;
if (titleChangedSinceLastGet() || (b=b*2%4))
at the first iteration b=2 while b=0 at the rest of them.
Are these blocks of code identical? By identical I mean, does the compiler interpret them exactly the same way?
int i = 2;
if (i == 0) {
System.out.println("0!");
} else if (i == 1) {
System.out.println("1!");
} else if (i == 2) {
System.out.println("2!");
} else {
System.out.println("?!");
}
int i = 2;
if (i == 0) {
System.out.println("0!");
} else {
if (i == 1) {
System.out.println("1!");
} else {
if (i == 2) {
System.out.println("2!");
} else {
System.out.println("?!");
}
}
}
As you can see this is Java.
While both my friend and I agree that logically these are exactly the same, I was wondering whether the java compiler compiles them exactly the same way. The thing that strikes me is that in the second else/if block you are nesting ifs and elses inside of the else block.
However, given my lack of knowledge in assembly or java byte code, this very well could compile to be completely identical. The only advantage could be syntactical sugar, if you will.
Will someone put this issue to rest - assuming you are extremely confident in the answer (otherwise another debate might ensue).
The two code samples differ only in the use of redundant curly braces, so I would be very suprised if different code is generated. But it's easy enough to check if you are really curious - use the javap command to display the bytecode.
if (dog.equalsIgnoreCase("yes")) {
drink.don.setCost(8.75);
drink.don.getType();
drin.l.add(drink.don.getType());
drink.c.add((double) coke.don.getCost());
cokeprice = coke + fanta.don.getCost();
else if (dog.equalsIgnoreCase("no"))
else catch(IllegalArgumentException iae) {
System.out.println("requires yes or no");
}
}
Ignore the stupid naming conventions had to change them, incase any class mates decided to steal anything ;p
I'm trying to get my if statement to allow the user input yes and do a condition, then if "no" has been entered then nothing happens just moves onto the next statement, then anything else is illegal and the program crashes.
I don't like throwing exceptions, especially if I expect that the user might type in something that I don't want. I'd rather do something like
if (userInput.equalsIgnoreCase("Yes")) {
// do yes
}
else if (userInput.equalsIgnoreCase("No")) {
// do no
}
else {
// Sorry, invalid input
}
I don't know what language you are using, nor do I know what any of the methods you are using do, but here is an example of a similar statement in C#.
First, use a method to convert the user input to a true or false (boolean) value:
public static bool IsYes (string userInput)
{
if (userInput == "yes')
{
return true;
}
else if (userInput == "no")
{
return false;
}
else
{
throw new CustomException();
}
}
Next, you can take the result of IsYes() and use it for the if else statement:
if (IsYes(userInput))
{
// code you want to execute if "yes"
}
else
{
// code you want to execute if "no"
}
Hopefully this code will give you an idea of how to use if-else statements, but in the future please explain your question more clearely. Remember, this is C#, so although if statements are similar in almost all languages some of the other code will differ. Also, this is just an example, it won't do anything on its own.