Type Declaration

Part of the Fundamentals section of Coddy's C++ journey — lesson 11 of 74.

In C++, once a variable is declared with a certain type, it can only hold values of that type. For instance, an int variable can only hold integer values, and a std::string variable can only hold text.

For example:

int age = 25;          // Can only hold whole numbers
string str = "abc";  // Can only hold text

These would cause errors:

age = "defg";  // Error: can't put text in an int variable
str = 25;      // Error: can't put a number in a string variable

These are valid:

age = 26;        // OK: assigning a new integer
str = "Jane";    // OK: assigning a new text string

Challenge

Beginner

Declare the following variables with their corresponding types and values:

An int variable named count with the value 10.
A double variable named total with the value 150.75.
A char variable named grade with the value 'A'.
A bool variable named isActive with the value false.
A string variable named userName with the value "Bob123".

After declaring these variables, output the values of the variables to the console in the following format:

Count: [value of count]
Total: [value of total]
Grade: [value of grade]
Active: [value of isActive]
User Name: [value of userName]

Cheat sheet

In C++, variables have fixed types and can only hold values of that specific type:

int age = 25;          // Can only hold whole numbers
string str = "abc";    // Can only hold text

Type mismatches cause errors:

age = "defg";  // Error: can't put text in an int variable
str = 25;      // Error: can't put a number in a string variable

Valid reassignments must match the original type:

age = 26;        // OK: assigning a new integer
str = "Jane";    // OK: assigning a new text string

Try it yourself

#include <iostream>
#include <string>
using namespace std;

int main() {
    // Declaring variables


    // Printing values
    cout << "Count: " << count << endl;
    cout << "Total: " << total << endl;
    cout << "Grade: " << grade << endl;
    cout << "Active: " << isActive << endl;
    cout << "User Name: " << userName << endl;

    return 0;
}

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

Type Declaration

Cheat sheet

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