I have an AutoHotkey script which includes a strange block of else-if statements:
if (x=1)
{
; ...
}
else
if (y=8)
{
; ...
}
Based on the documentation for if statements, I can think of two ways to interpret this:
1) An else-if statement:
if (x=1)
{
; ...
}
else if (y=8)
{
; ...
}
2) An if statement inside an else block
if (x=1)
{
; ...
}
else
{
if (y=8)
{
; ...
}
}
What is the behavior when else and if are separated by newlines?
Related
If I am enclosing the code after first if upto second return in curly braces it is not giving me desired output.
static int comparator(Player a, Player b) {
if(a.score == b.score)
if(a.name == b.name)
return 0;
else
return (a.name > b.name)? -1:1;
return (a.score < b.score)? -1:1;
}
Your code has if() and else statements. Each will execute one line of code that comes after them. This means that it will only execute a single statement and end after the first ; that it finds.
for() loops, while() loops, if-else blocks can be used without curly braces if the statement you want to execute consists of only one line of code following them.
Your code works as -
static int comparator(Player a, Player b) {
// if statement without braces- means just one statement executes
if(a.score == b.score)
// Remember if-else will be considered as a single code block so both will run
if(a.name == b.name)
return 0;
else
return (a.name > b.name)? -1:1;
// This statement will run only when the above if condition is not satisfied
return (a.score < b.score)? -1:1;
}
This can be considered to be same as -
static int comparator(Player a, Player b) {
if(a.score == b.score) {
if(a.name == b.name) {
return 0;
} else {
return (a.name > b.name) ? -1 : 1;
}
}
return (a.score < b.score) ? -1 : 1;
}
NOTE : It is generally better if you use the braces as it will be good for readability as well as maintainability of the code. There can actually be two way of parsing it - Dangling else(though most compiler will associate the else with closest if).
In this coding style, there's no way to differentiate between below two code -
if(condition1)
if(condition2)
foo1();
else
foo2();
and,
if(condition1)
if(condition2)
foo1();
else
foo2();
Since, in C/C++, it doesn't consider the indentation in code, so it might create ambiguity while reading the code. So its always better to use curly braces instead of doing it like above. Drop them only when you have a single line and it won't create any confusion reading the code later on...
Hope this helps !
Without curly braces, only the next statement is executed. With proper indentation it becomes easier to see what's going on:
static int comparator(Player a, Player b) {
if(a.score == b.score)
if(a.name == b.name)
return 0;
else
return (a.name > b.name) ? -1 : 1;
return (a.score < b.score) ? -1 : 1;
}
This is actually the same as:
static int comparator(Player a, Player b) {
if(a.score == b.score) {
if(a.name == b.name) {
return 0;
} else {
return (a.name > b.name) ? -1 : 1;
}
}
return (a.score < b.score) ? -1 : 1;
}
You have maybe used the braceless else variant without noticing it when writing something like:
if(condition) {
//
} else if(another_condition) {
//
} else {
//
}
Which is actually the same as
if(condition) {
//
} else {
if(another_condition) {
//
} else {
//
}
}
Without curly braces, the if guard only applies to the immediate next statement.
It's just how the language works. :/
I'm trying to write a .clang-format file that will allow the following:
if (value.Is<bool>()) { index = 1; }
else if (value.Is<int>()) { index = 2; }
else if (value.Is<unsigned int>()) { index = 3; }
else if (value.Is<long long>()) { index = 4; }
else if (value.Is<unsigned long long>()) { index = 5; }
else if (value.Is<float>()) { index = 6; }
else if (value.Is<double>()) { index = 7; }
else if (value.Is<long double>()) { index = 8; }
else if (value.Is<std::string>()) { index = 9; }
else if (value.IsArray()) { index = 10; }
else { index = 0; }
I've tried every option I can find related to breaks and allowShort*, and no matter what I do it seems to split them into multi-lines after the first like so:
if (value.Is<bool>()) { index = 1; }
else if (value.Is<int>()) {
index = 2;
}
...
Is there some option I'm missing that could support this?
Unfortunately, this is currently not supported for if-else statements, only for simple if's (as of revision 329373, dating 6/4/18). The AllowShortBlocksOnASingleLine and AllowShortIfStatementsOnASingleLine options are not applicable for if-else statements.
Hopefully this will change in the future.
The doc is not explicit about this, saying that AllowShortIfStatementsOnASingleLine will allow simple if statements on a single line:
AllowShortIfStatementsOnASingleLine (bool)
If true, if (a) return; can be put on a single line.
However, clang-format code suggests that if-else blocks are not allowed on single lines:
1) UnwrappedLineFormatter.cpp, tryMergeSimpleControlStatement:
// Only inline simple if's (no nested if or else).
if (I + 2 != E && Line.startsWith(tok::kw_if) &&
I[2]->First->is(tok::kw_else))
return 0;
2) FormatTest.cpp, FormatShortBracedStatements test.
Notice the test parameters, and that in the expected formatting in the unittests, else always resides in its own line, while plain if statements with no else are on a single line with their blocks, for example:
verifyFormat("if (true) {\n"
" f();\n"
"} else {\n"
" f();\n"
"}",
AllowSimpleBracedStatements);
https://clang.llvm.org/docs/ClangFormatStyleOptions.html says:
SIS_AllIfsAndElse (in configuration: AllIfsAndElse) Always put short ifs, else >ifs and else statements on the same line.
if (a) return;
if (b) return;
else return;
if (c) return;
else {
return;
}
Is it possible to make multiple if's and one else for all of them without using the bool variable? I'm talking about something that works like this:
bool triggered = 0;
if (condition)
{
//code
triggered = 1;
}
if (condion2)
{
//code
triggered = 1;
}
if (!triggered)
{
//code
}
So if none of these if's happened - something happens. In pseudo-code I would write it like this:
{
if()
{
}
if()
{
}
}
else
{
}
Is there a possibility to make something similar?
No, you can't do it like that. You can do:
if (condition1 || condition2) {
if (condition1) {
//code
}
if (condition2) {
//code
}
} else {
// code
}
But this means you have to test condition1 and condition2 twice. And if there are lots of conditions, the first if will be very long.
I find your code with the triggered variable preferable. Often, there's already a variable that serves the purpose. For instance, form validation code often looks something like this:
std::string errors;
if (field1 is invalid) {
errors += "Field1 is invalid\n";
}
if (field2 is invalid) {
errors += "Field 2 is invalid\n";
}
if (errors == "") {
// process the form
} else {
// display error message
}
This is not about an existing piece of code but I'm looking for some pattern that may exist in the case that some nested if perform the same thing in their else statement.
if(condition1(a)) {
doSomethingWith1(a);
if(condition2(a)) {
doSomethingWith2(a);
} else {
elseFn();
}
} else {
elseFn();
}
The doSomethingWith... functions are changing the value of a, making it complex to have all the condition in one if.
So I'm just wondering if there is a clearer way to write it (in C, if possible).
Thanks guys
in your case, looks like the first if, if(condition1(a)), is absolutely necessary to test for the value of a before calling doSomethingWith1(a); to avoid an exception. so, no, there is no other way to do it.
if(condition1(a)) {
doSomethingWith1(a);
if(condition2(a)) {
doSomethingWith2(a);
} else {
elseFn();
}
} else {
elseFn();
}
You could just keep a count of the "doSomethings" and invoke the elseFn unless all were executed.
int count = 0;
if (condition1(a)) {
doSomethingWith1(a);
count++;
if (condition2(a)) {
doSomethingWith2(a);
count++;
if (condition2(a)) {
doSomethingWith2(a);
count++;
}
}
}
if (count < 3) {
elseFn();
}
I find it more readable, though less efficient, to double-check the first condition. This refactoring eliminates nesting, without multiple functions. It also more clearly shows three distinct paths of execution by grouping each logical path into a single code block.
if (condition1(a) && condition2(a)) {
doSomethingWith1(a);
doSomethingWith2(a);
}
else if (condition1(a)) {
doSomethingWith1(a);
elseFn();
}
else {
elseFn();
}
I don't know in C but in Java you could write this as the following:
void function(int a) {
boolean b1 = condition1(a);
if (b1) {
doSomethingWith1(a);
boolean b2 = condition2(a);
if (b2) {
doSomethingWith2(a);
}
}
if (b1 || b2) {
return;
}
elseFn();
}
if (BT_IS_SUCCESS(xCode))
{
if (!(BT_IS_SUCCESS(xCode)))
{
else
{
if ()
{
}
}
}
}
I m trying to insert a newline before every if - statement in an intended code base.
whenever i insert newline using \r the white spaces are not retained.
I m currently using
:1,$ g/;\nif (
:%s//;\r\rif
Here new-lines are inserted but to retain same number of white spaces what options are available .
Thanks in advance
does this help?
:g/if (/normal O
If you want to turn this:
function dummy() {
if (true) {
return true;
else {
return false;
}
if (true) {
return true;
else {
return false;
}
}
into that:
function dummy() {
if (true) {
return true;
else {
return false;
}
if (true) {
return true;
else {
return false;
}
}
one solution is to do:
:g/if (/norm! O
or you could do:
:g/if (/put!=''