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I am sorting my vector of strings in the following way, so that I can binary_search it later.
std::vector<std::string> vec;
...........
...........
std::sort(vec.begin(),vec.end());
Now I am searching it as follows.
if (!std::binary_search(vec.begin(), vec.end(), "SomeString"));
{
//Not Found
}
else
{
//Found
}
However, it seems that the binary_search is not working, and it returns a false to the "strings" that are present in the vector.
What might I be doing wrong?
Look at the very last character on this line:
if(!std::binary_search(vec.begin(),vec.end(),"SomeString"));
You have a misplaced ; there. Remove it and test again.
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I am curious as though, why when I use an array in for-loop in the given manner below, the inner loop only runs once.
Thank you for your reply.
#include<iostream>
using namespace std;
int main(){
int a[2]={0};
a[0]=5;
for(a[0];a[0]<10;a[0]+=1){
for(a[1];a[1]<10;a[1]+=1){
cout<<a[0]<<" "<<a[1]<<endl;
}
}
}
You are never resetting a[1], so once it hits 10 the first time through the inner loop, it will never execute again. Modify to for(a[1]=0;a[1]<10;a[1]+=1){
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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
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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]
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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));
// ^
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I have a queue of vector and want to the front of the queue to another vector , but it is showing an error . How could i accomplish this task ?
queue< vector<int> > que;
vector<int> vec;
vec = que.front() ;
vec = que.pop();
Showing error in the third line .
std::queue::pop doesn't return any value
Assuming que.front is a typo, you missed function call ()
You have an error in your syntax, it should be vec = que.front();
More reference can be found in this link.