How to get the Index of Specified Item in a Vector in C++ - Step by Step Examples

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How to get the Index of Specified Item in a Vector in C++ ?

Answer

To get the index of a specified item in a vector in C++, you can use algorithms like std::find or std::find_if.

✐ Examples

1 Find Index of Specified Item in Numeric Vector

In this example,

We have a vector named vec containing numeric elements.
We use the std::find algorithm from the algorithm header to search for the specified item.
If the item is found, std::find returns an iterator pointing to the found element. We calculate the index by subtracting the beginning iterator from the found iterator.
Finally, we print the index to standard output.

C++ Program

#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    std::vector<int> vec = {1, 2, 3, 4, 5};
    int item = 3;
    auto it = std::find(vec.begin(), vec.end(), item);
    if (it != vec.end()) {
        int index = std::distance(vec.begin(), it);
        std::cout << index << std::endl;
    }
    return 0;
}

Output

2 Find Index of Specified Item in String Vector

In this example,

We have a vector named vec containing string elements.
We use the std::find algorithm from the algorithm header to search for the specified item.
If the item is found, std::find returns an iterator pointing to the found element. We calculate the index by subtracting the beginning iterator from the found iterator.
Finally, we print the index to standard output.

C++ Program

#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    std::vector<std::string> vec = {"apple", "banana", "cherry", "date"};
    std::string item = "banana";
    auto it = std::find(vec.begin(), vec.end(), item);
    if (it != vec.end()) {
        int index = std::distance(vec.begin(), it);
        std::cout << index << std::endl;
    }
    return 0;
}

Output

Summary

In this tutorial, we learned How to get the Index of Specified Item in a Vector in C++ language with well detailed examples.

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How to get the Index of Specified Item in a Vector in C++ - Step by Step Examples

How to get the Index of Specified Item in a Vector in C++ ?

Answer

✐ Examples

1 Find Index of Specified Item in Numeric Vector

C++ Program

Output

2 Find Index of Specified Item in String Vector

C++ Program

Output

Summary

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