How to Iterate Over a Vector with Index in C++

How to Iterate Over a Vector with Index in C++ ?

Answer

To iterate over a vector with index in C++, you can use a standard for loop with an index variable ranging from 0 to the size of the vector minus one.

✐ Examples

1 Iterate Over a Numeric Vector with Index

In this example,

We create a vector named num_vec containing several numeric values.
We use a standard for loop to iterate over the vector. The loop variable i ranges from 0 to num_vec.size() - 1, where num_vec.size() returns the number of elements in the vector.
Within the loop, we access each element of the vector using the index i and print both the index and the corresponding value to the standard output.
This method ensures that we can iterate over the vector while having access to the index of each element.

C++ Program

#include <iostream>
#include <vector>

int main() {
    std::vector<int> num_vec = {10, 20, 30, 40, 50};
    for (size_t i = 0; i < num_vec.size(); ++i) {
        std::cout << "Index: " << i << " Value: " << num_vec[i] << std::endl;
    }
    return 0;
}

Output

Index: 0 Value: 10
Index: 1 Value: 20
Index: 2 Value: 30
Index: 3 Value: 40
Index: 4 Value: 50

2 Iterate Over a String Vector with Index

In this example,

We create a vector named str_vec containing several strings.
We use a standard for loop to iterate over the vector. The loop variable i ranges from 0 to str_vec.size() - 1, where str_vec.size() returns the number of elements in the vector.
Within the loop, we access each string element of the vector using the index i and print both the index and the corresponding string to the standard output.
This approach allows us to iterate over the string vector while having access to the index of each string.

C++ Program

#include <iostream>
#include <vector>
#include <string>

int main() {
    std::vector<std::string> str_vec = {"apple", "banana", "cherry", "date"};
    for (size_t i = 0; i < str_vec.size(); ++i) {
        std::cout << "Index: " << i << " Value: " << str_vec[i] << std::endl;
    }
    return 0;
}

Output

Index: 0 Value: apple
Index: 1 Value: banana
Index: 2 Value: cherry
Index: 3 Value: date

Summary

In this tutorial, we learned How to Iterate Over a Vector with Index in C++ language with well detailed examples.

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How to Iterate Over a Vector with Index in C++

How to Iterate Over a Vector with Index in C++ ?

Answer

✐ Examples

1 Iterate Over a Numeric Vector with Index

C++ Program

Output

2 Iterate Over a String Vector with Index

C++ Program

Output

Summary

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