Creating vector of vector of complex numbers [closed] - c++

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I'm attempting to create a vector of vectors of complex numbers, however it will not work, previous research indicates that the following should work
vector <vector <complex<double> > test(1,vector<complex<double> >(3));
it does not
I can't figure out why and I am going crazy trying to figure out why, I get the following error
error: template argument 1 is invalid
Can anyone figure out why?

You are missing one >:
vector<vector<complex<double> > > test(1, vector<complex<double> >(3));
// ^

Related

Meaning of vector<string = ">v; while declaring vector with data string [closed]

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In C++, please explain meaning of string = "" in vector declaration -> vector<string = "">v;
Assuming these are std::vector and std::string, it is syntactically invalid. It won't compile.
Otherwise, you need to provide more context like: what are vector, string and v? Are they objects? Objects of what type? Are they macros? Are they classes? Are they templates? It could do anything. Here it prints Hello, World, here it calculates pi, here it creates a std::vector of std::string, and here it doesn't compile.

Ereasing a particular char from whole std::string [closed]

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I wanted to clear string from unwanted chars, and I tried to iterate it through a loop like this.
for(auto it=numer.begin(); it!=numer.end(); ++it)
{
if(*it=='-') numer.erase(it);
}
The error is: "expected primary-expression before '=' token";
I could, of course, I could do this with [] operator. But I am wondering why it doesn't work.
I appreciate your help.
If you want to remove all instances of a character from a string, a simple way to do that would be to use the standard erase-remove(if) idiom:
numer.erase(std::remove(numer.begin(), numer.end(), '-'), numer.end());
See also:
https://en.cppreference.com/w/cpp/string/basic_string/erase
https://en.cppreference.com/w/cpp/algorithm/remove

C++ error: decomposition declaration not permitted in this context [closed]

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Why is g++ giving an error like this?
blahblah.h:80:10: error: decomposition declaration not permitted in this context
float[NUM_OUTPUTS] output_buffer;
(Already solved, but creating this because there's no good google hits for this error text, and the error message is inscrutable.)
In C++ declarations, the array size goes after the variable name, not after the type:
float output_buffer[NUM_OUTPUTS];

python: check if all elements the same in an list [closed]

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Closed 6 years ago.
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I am using the following code to check if all the elements in a list are the same:
def sameItem(myList):
return all(x==myList[0] for x in myList)
However, in my test case:
myL1 = ['dog','cat','dog']
sameItem(myL1)
returns True. Shouldn't it be False? Or did I have a bug in the sameItem() function?
Also, I am using Jupyter Notebook, could it cause any problem is this scenario?
Thanks!
Your method should be correct and works for me. As an alternative, you can try this method to double check, which is a one line that does the same thing
return myList[1:] == myList[:-1]

do_trucate in jinja2, correct usage needed [closed]

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Closed 7 years ago.
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I think I saw something on using this to truncate test as a filter, but I've seen to no idea how to use it. Using as xx|do_trucate(20) gives the following:
TemplateAssertionError: no filter named 'do_truncate'
What is the correct usage?
Doh, from the spec I saw
do_trucate
http://code.nabla.net/doc/jinja2/api/jinja2/jinja2.filters.html
But in reality, its just truncate