Questions tagged [range-based-loop]
66 questions
0
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2 answers
C++ Why are my Objects being destroyed, and sometimes twice in a row when using range based for loop
I'm a beginner programmer looking to understand why my objects are being deleted, sometimes even twice. I'm trying to avoid creating them on the heap for this project as that is a more advance topic I will try at a later time.
Whats causing the…
Chavon4
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- 3
0
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3 answers
C++ iterating and range-for-loop differences
I have a chunk of C++ code that is supposed to go through a sorted vector and delete reoccurring objects in-place. I completed the task (C1) using an iterator. I continued with the problem and wanted to do it using range-based for loop like the…
0
votes
1 answer
How to iterate through a range-based for loop when the data type of the array is const char *?
I am trying to solve the following question:
https://www.codewars.com/kata/54bf1c2cd5b56cc47f0007a1/train/cpp in C++.
When I try to iterate over a range based for loop I get the following error ->
In file included from…
user14925305
0
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1 answer
Custom class range based for-loop over a 2D map
I have the following class MyClass that contains a 2D map (std::map>).
I would like to know if it is possible to implement the MyClass::begin() MyClass::end() functions for MyClass in order to have a…
romain.bqt4
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2 answers
Why doesn't sorting work for an iterator in Map?
So here is my code; I find the sort doesn't work for the vector in this map. Does anyone know why?
The output of this code is still "3 1 2 4 5"
map > values;
values[1] = {3,1,2,4,5};
for(auto g: values) {
sort(g.second.begin(),…
2997ms
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- 3
0
votes
1 answer
Dynamically update range inside loop by overload end() method
I want to create a class to store data also dynamically - inside a range based loop. But I face problem to overload end() method. The idea is something like:
template
class ContainerClass
{
public:
typename std::vector::iterator…
Assen
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- 2
0
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2 answers
Can you avoid out of range error if you use range based for loop instead of the standard for loop?
I was experimenting around with range-based for loop found that if you use range-based for loop to loop through a vector it runs into out of range error is there any way to avoid this error if you are using range-based for loop
int main()
{
…
AUNG
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- 7
0
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1 answer
Updating class member values inside a range based for loop in C++
The code on top works. The code below it does not. Why?
I am searching through a vector of class objects in C++ using the object's name member so as to increment it's watched member. The regular for loop and syntax successfully increments the…
Seth Van
- 25
- 7
0
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2 answers
Accessing references to existing object in a range based for loop with structured binding
I am struggling to find an easy solution to alter some already existing objects.
Lets assume I have the following pairs
std::pair p1 = {1,foo()};
std::pair p2 = {2,foo()};
std::pair p3 = {3,foo()};
with foo being a…
someOtherPhysicist
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- 3
0
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4 answers
In a C++ range-based for loop, can begin() return a reference to a non-copyable iterator?
Update:
Thanks to everyone who submitted an answer.
In short, the answer is that the "iterators" that begin() and end() return must be copyable.
Artyer proposed a nice workaround: Make an iterator class that contains a reference (or, alternatively,…
mpb
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0
votes
2 answers
Difference between for loop and the range based loop in C++
I am confused as to what what the difference is between for loop and for each loop in C++.
I read tutorials and some books but I am yet to see how for each loop is different.
With arrays, examples I have seen seem to suggest for each loop loops…
Mallam Awal
- 223
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-1
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1 answer
Get a random number when emplace an element with range-based for loop
I wrote a program to insert the numbers in C++ with CLion.
First, enter a set of positive integers and place them into the vector called pour.
Then, take the negative numbers of these positive integers and then emplace them into the pour.
However,…
抹茶抹茶
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-1
votes
1 answer
How to make a spaced line of strings from a vector in C++
I want to make a line like this hello my name sounds very fancy from a vector of these words (std::vector myvector = {"hello", "my", "name", "sounds", "very", "fancy"}).
What is the most efficient way to perform such convertion without…
SharkyMonkey
- 19
- 3
-1
votes
1 answer
Multidimensional arrays
I was curious about why we go through a multidimensional array this way
for (auto& row : mat1)
{
for (int& elements : row)
{
cin >> elements;
}
}
Why do we use &(pass by ref) when we make a temp variable…
Zoon
- 19
- 1
-1
votes
1 answer
Why is my range-based for loop working for some data types but not others?
I tried out some range-based for loops to get an idea of the concept and for arrays and vectors of integers, it works fine. But for a vector of characters, my compiler does not give any error messages or the desired result, just a line of red dots.…
Allen Ding
- 11