How to use std::adjacent_find()

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Hi
Lets say I have structure

C++

struct MyData{
  long id;
  whcar_t name[64];
  wchar_t data[256];
};

typedef std::vector<mydata>  MyData_t;

MyData_t dataArray;

dataArray contains data

C++

{ {1;L"First";L"Data1"}, {2;L"Second";L"Data2"}, {4;L"Fourth";L"Data4"}}

Now I want to find out is id(for example 3) used in this array.

How can I do that with std::adjacent_find() ?

What I have tried:

std::adjacent_find(dataArray.begin(), dataArray.end(), ????? )

Posted 18-Jun-21 3:01am

NoviceEx

Updated 18-Jun-21 3:31am

CPallini

v2

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CPallini 18-Jun-21 9:34am

adjacent_find searches for two consecutive equal values. Are you sure is what you need?

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Richard MacCutchan · Answer 1 · 2021-06-18T03:30:00

Solution 1

You need to provide a custom predicate function to do the comparisons. See std::adjacent_find - cppreference.com[^].

Posted 18-Jun-21 3:30am

Richard MacCutchan

Comments

NoviceEx 18-Jun-21 9:56am

and I was not able to do that, probably I do not get something

if I use std::find_if then I can do it

const auto& found = std::find_if(dataArray.begin(),
dataArray.end(),
[&Id](const MyData &md) { return md.id == Id; } );
if( found == dataArray.end() )
return Id;

How to do that with std::adjacent_find()?

Richard MacCutchan 18-Jun-21 10:02am

You do not have two adjacent items with the same id.