I am using CLion IDE to code my C++ project. Sometimes it happens that the IDE tries to be more intelligent than me and gives me suggestions. I have a simple problem during code inspection (by CLion). It says the following code can be simplified, even though I believe it is the most simple form I can think of :
Code :
if (node.first >= 0 && node.first <= 45 &&
node.second >= 0 && node.second <= 30)
return true;
else
return false;
Assume node is of type std::pair<int, int>
The suggestion I get from the CLion IDE is the following:
Code Inspection comments :
Inspection info: This inspection finds the part of the code that can be simplified, e.g. constant conditions, identical if branches, pointless boolean expressions, etc.
Do you think this can be simplified more ?
CLion is hinting at you that this bit...
if (node.first >= 0 && node.first <= 45 &&
node.second >= 0 && node.second <= 30)
return true;
else
return false;
could just be re-written as
return node.first >= 0 && node.first <= 45 &&
node.second >= 0 && node.second <= 30;
Since an expression used as a condition in a control statement obviously has a natural conversion to true and false.
Related
Any idea why the else if statment will be never executed ? The value of difference is constantly changing when the program runs.
double difference = abs(reale_x[0] - reale_x[1]);
if (0 <= difference < 45) {
timer_counter += 1;
if (timer_counter == 30) {
cout << "CLICK" << '\n';
}
}
else if (difference > 50) {
timer_counter = 0;
}
That is not how comparation works in c++.
What this code
if (0 <= difference < 45) {
does is it first compares if 0 is smaller or equal to difference. It is then "replaced" by a bool value either true or false. And then a bool value (so either 1 or 0) is compared to 45. And it will always be smaller than 45. What you have there is an always true statement.
So the way you would write this if statement is
if (difference >= 0 && difference < 45){
Note that because of your else if statement it will not execute if the difference is >44 and <51
if (0 <= difference < 45) will be executed as if ((0 <= difference) < 45), which will be either 0<45 or 1<45 and will always be true. That's why the else part is not getting executed.
in mathematics, we see and write 0 <= x < 45 or something like that to define the range of the variable x. But in order to tell the computer the same thing, you have to tell more clearly. Saying, to have to tell the compiler, that the value of x is greater than or equal to zero and at the same time, that value will be less than 45, and you can tell the compiler by this statement: difference >= && difference < 45 . the && is an 'AND' operator in most of the languages.
I would like to avoid incrementing and decrementing in if-statement since there is a segmentation fault error in the following code while checking conditions (if we start with p = 1 and k = 1 for example):
if (((heights[k--][p--] < heights[k][p]) || (heights[k--][p--] == heights[k][p])) &&
((heights[k--][p++] < heights[k][p]) || (heights[k--][p++] == heights[k][p])) &&
((heights[k++][p--] < heights[k][p]) || (heights[k++][p--] == heights[k][p])) &&
((heights[k++][p++] < heights[k][p]) || (heights[k++][p++] == heights[k][p]))){
width[k][p] = 3;
}
For example, the second check fails with k = -1.
I would like to check neighbouring elements of a two-dimensional array heights in an if-statement and than run some logic in case it was true.
How can I optimise it and generally rewrite it to make it look (and work) better? I haven't found any information on it.
As others have indicated, replacing 'k--' with 'k-1' and 'k++' with 'k+1' for all 'k' and 'p' variables may resolve the segmentation error. 'k+1' is a reference to the next array index after 'k', while 'k++' increments the value of 'k' after it's used. It's also good programming practice to avoid using expressions as arguments.
https://en.cppreference.com/w/cpp/language/operator_incdec
To clean up the code, you could also simplify the logical OR by replacing '<' with '<='.
if ((heights[k-1][p-1] <= heights[k][p]) &&
(heights[k-1][p+1] <= heights[k][p]) &&
(heights[k+1][p-1] <= heights[k][p]) &&
(heights[k+1][p+1] <= heights[k][p])){
width[k][p] = 3;
}
I'm new to C++ and before learn C++ I have learned pascal. I have to keep repeat the input process until this condition is satisfied (1 <= m <= n <= 1000000000, n-m<=100000) in pascal it's pretty easy with the "repeat... until" command but in C++ there is only "while" which only stop when the condition is false
Just put your conditions in a while loop separating each condition with && if you want both conditions to result true:
try this:
while(!(m>=1 && n>=1 && n<=1000000000 && (n-m) <=100000)){
// your code here
}
while(true){
if(m>=1 && n>=1 && n<=1000000000 && (n-m) <=100000)
break;
// do something
}
1.Imagine condition if (obj.is_x() || obj.is_y() || obj.is_z())
Will obj.is_y() and obj.is_z() be called and evaluated if obj.is_x() returned true ?
2.Is this a bad idea(in general)? Does this code look bad ?
bool isbn13_prefix_valid (const string& prefix)
{
unsigned num = stoi(prefix);
if (num == 978 || num == 979) return 1; //super common ones
else if ( num >= 0 && num <= 5 || num == 7 || num >= 600 && num <= 649
|| num >= 80 && num <= 94 || num >= 950 && num <= 989
|| num >= 9900 && num <= 9989 || num >= 99900 && num <= 99999)
return 1;
return 0;
}
No, it will not, due to short-circuiting.
Yes, that code looks bad. Not because it's incorrect, but because you're stuffing an extremely long conditional into a single if statement. Try refactoring your code to make it cleaner.
Your code is absolutely fine. I'd like to see a comment where these strange numbers come from, that's all.
Turning it into a dozen trivial functions as has been suggested is in no way helpful. It actually makes it a lot harder to read the code, because it gets spread out over many many lines of code. Yes, it is complex. But that's due to the problem being complex, and trying to spread the complexity out doesn't help one bit.
Your actual question: In a || b, a is evaluated first. If it is true, then b is not evaluated and the result is true. If a is false, then b is also evaluated and the result is true or false, depending on the result of b.
An optimising compiler may start evaluating b before it has finished evaluating a, if it can prove that the evaluation of b has no side effects, and if it believes that (mostly due to parallelism in the hardware) it is on average faster to evaluate as much in parallel as possible, even if some things are evaluated when it wasn't necessary. But this is not noticable in the results of your code, and will only make the code faster.
I have the following problem
in my app i have severeal if-statements
if ( (number >= 1 && number <= 18) && !strcmp("half1-18", _myBetCh) ) {
}
Now I realized that I have to split this condition because I need a boolean variable after one condition
bool success = false,
if(!strcmp("half1-18", _myBetCh) {
success = true;
if (number >= 1 && number <= 18) {
}
}
Is there a workaround to this? Is it possible, for instance, to make an assignment withing the if-statement?
It's possible, like this:
if ((success = !strcmp("half1-18", _myBatCh)) && number > 1 && number < 18)
but I personally think assignments in conditions are messy and hard to read, and prefer this variation:
bool success = strcmp("half1-18", _myBetCh) == 0;
if (success && number >= 1 && number <= 18) {
// ...
}
Well, there is:
if ( !strcmp("half1-18", _myBatCh) && (success = true, number > 1 && number < 18) )
or, obviating the need for the success = false earlier
if ( (success = !strcmp("half1-18", _myBatCh)) && number > 1 && number < 18 )
Your way is easier to read though, so I would consider sticking with what you've got.