Friday
C++Simple Data Structure - The Vector
The vector is a simple data structure that allows you to store values with the same data type in one container.
Introduction
Without the use of a data structure, how would you store multiple variables? Let’s say we wanted to store 5 names into strings. How would this be done?
cin >> name1 >> name2 >> name3 >> name4 >> name5;
That looks a bit ugly doesn’t it? What if we wanted to store the number of names the user wanted to input? That is where the vector comes in.
The Vector
//Syntax:
vector <data_type> name;
To populate our vector with 5 names, we would simply do the following:
string input;
for ( int i = 0; i < 5; i++ ) {
cin >> name;
names.push_back(input);
}
In other words, we simply ask the user five times with our for loop, to type in the terminal a name, and it will be push_back‘ed onto our vector. Every single time we use the push_back member function of the vector, we simply push the newly inserted element to the back. Let’s use the following visual example of a vector.
Notice how the positions are labeled. The size of the vector is the number of elements in the vector. To create this vector, we would do the following.
names.push_back("Joe");
names.push_back("Beth");
names.push_back("Mary");
names.push_back("Jon");
names.push_back("Sue");
How would we access and print out a variable?
Printing out elements of the vector
To print out an element we would simply do the following:
This allows us to print out the value that is contained in position zero. Therefore, “Joe”.
To find out the size of our vector we would simply do:
This would print out 5 since our vector contains 5 elements.
To remove an element from our vector we would simply do:
This would remove “Sue” from our vector, giving it a size of 4.
Doing more with the vector
Challenge 1: Populate a vector with 5 integer values, and print them all out.
Challenge 2: Print out all the elements of a vector using a for loop.
What now?
Join our forums and discuss your newly discovered vector! Remember, there is still so much more to learn with how to use a vector, this is simply a tutorial for beginners and isn’t meant for advanced users.
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