Sorting of vector according to a string which contains date in a particular format

[kunalg]

hi all ,

i want to sort the vector according to a string and the string according to which i want to sort the data is date ( in a pre defined format) . Now whats the best way to do it...


i can think of using qsort.. is there any better way to do sorting..

thanks in advance guys..

[Ganon11]

qsort is probably the best way to perform this sort. Not only is the quicksort a relatively fast sorting algorithm, but qsort has already been written for you, so you don't need to test if it works on your own.

[weaknessforcats]

If you have a vector, then use the sort algorithm.

You pass in iterators to the begion and end of the sort range and a binary predicate. A binary predicate here would be a function that that takes two vector elements as arguments and returns true if first arg < last arg. The function determines what < means. Here's where you can use your string.

You will have to #include <algorithm>

Avoid qsort. According top Scott Meyers sorting a vector of a million doubles, using sort with an inline comparison function is 670% faster than qsort since qsort must actually call the comparison function each time.

[kunalg]

hi ,

thanks for the quick reply

but i am getting following error while using the sort function. Do anyone have any idea how to resolve this error?

Could not find a match for std::sort<std::RandomAccessIterator, std::Compare>(ShiftData*, ShiftData*, bool(ShiftData&,ShiftData&)) needed in CapExtrc::getAdjustTechShift(std::vector<ShiftData >).

i have passed the following argument to the function

sort(techShiftPriority0.begin(),techShiftPriority0 .end(),compareTechShift);

compareTechShift is declared the follwing way:


bool CapExtrc::compareTechShift(techShiftData &a , techShiftData &b);

and vector is declared as follows:

vector<techShiftData> techShiftArray;

[weaknessforcats]

This code:

sort(techShiftPriority0.begin(),techShiftPriority0 .end(),compareTechShift);
 

I think must need to be:

sort(techShiftArray.begin(),techShiftArray.end(),compareTechShift);
 

Try that.

[kunalg]

This code:

sort(techShiftPriority0.begin(),techShiftPriority0 .end(),compareTechShift);
 

I think must need to be:

sort(techShiftArray.begin(),techShiftArray.end(),compareTechShift);
 

Try that.

No you get it wrong or actually i posted it wrongly. techShiftArray is just a variable name for the vector and variable name is

vector<techShiftData> techShiftPriority0,techShiftPriority1,techShiftPri ority2;

where i have to sort these three vector.

i am not able to get from the message that why it is saying that it is not able to find and showing only one randomIterator, although i am passing two randomIterator.

[kunalg]

i am also getting the same error while sorting the

bool compareInt( int a , int b)
{
return (a> b)
}


vector< int > vint;

vint.push_back(2);
vint.push_back(6);
vint.push_back(4);


sort(vint.begin(),vint.end(),compareInt);

any idea guys i am getting this error:


nclude -I/usr1/arbor//oam_src/include -c CapExtrc.cpp -o CapExtrc.o
"CapExtrc.cpp", line 1214: Error: Could not find a match for std::sort<std::RandomAccessIterator, std::Compare>(int*, int*, bool(int,int)) needed in CapExtrc::getAdjustTechShift(std::vector<shiftData >).

[kunalg]

btw i have solved the problem... the problem is that i am defining comparison inside my class and when i try to pass that function to the sort fuction, then sort function is not able to find that function because the function is defined in the scope of the class.

if anyone needs more explantion please leave a message for me..

[Alm]

btw i have solved the problem... the problem is that i am defining comparison inside my class and when i try to pass that function to the sort fuction, then sort function is not able to find that function because the function is defined in the scope of the class.

if anyone needs more explantion please leave a message for me..

Hi kunalg,

I am facing a similar problem.

I too made the comparison function out of the class scope after reading your post.

However I get an error that says implicit declaration of function int sort()

Did you face anything like that?

-Alm

[Alm]

Hi kunalg,

I am facing a similar problem.

I too made the comparison function out of the class scope after reading your post.

However I get an error that says implicit declaration of function int sort()

Did you face anything like that?

-Alm

SORRY MY BAD !! I had not included <algorithm>