C++ Numbers and Strings

In C++, the + operator serves two distinct purposes: adding numeric values and combining (concatenating) text values (strings). This is a powerful feature, but knowing how C++ treats numbers and strings differently is vital to avoid errors.

Adding Numbers

When the + operator is used with numbers, C++ performs mathematical addition.

Example

#include <iostream>
using namespace std;

int main() {
    int maxRPM = 10000;  // Engine's maximum revolutions per minute
    int idleRPM = 900;   // Engine's idle revolutions per minute

    int totalRPM = maxRPM + idleRPM;  // Adds numbers together
    cout << "Total RPM: " << totalRPM;

    return 0;
}

C++
​x
 
#include <iostream>using namespace std;​int main() {    int maxRPM = 10000;  // Engine's maximum revolutions per minute    int idleRPM = 900;   // Engine's idle revolutions per minute​    int totalRPM = maxRPM + idleRPM;  // Adds numbers together    cout << "Total RPM: " << totalRPM;​    return 0;}​

Output: This program calculates and displays “Total RPM: 10900”.

Combining Strings

When the + operator is used with strings, it performs concatenation, joining strings to form one.

Example

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

int main() {
    string helmetBrand = "Shoei ";
    string helmetType = "Full Face";

    string fullHelmetInfo = helmetBrand + helmetType;  // Combines text
    cout << "Helmet Info: " << fullHelmetInfo;

    return 0;
}

C++
 
#include <iostream>#include <string>using namespace std;​int main() {    string helmetBrand = "Shoei ";    string helmetType = "Full Face";​    string fullHelmetInfo = helmetBrand + helmetType;  // Combines text    cout << "Helmet Info: " << fullHelmetInfo;​    return 0;}​

Output: This combines “Shoei “ and “Full Face” to display “Helmet Info: Shoei Full Face”.

Adding Numbers and Strings Together

Attempting to combine numbers and strings directly with the + operator will cause an error, as C++ cannot perform both addition and concatenation simultaneously.

Example

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

int main() {
    string bikePrice = "100000";  // Price stored as text
    int discount = 5000;          // Discount stored as a number

    // Uncommenting the following line will cause a compilation error
    // string totalPrice = bikePrice + discount;

    return 0;
}

C++
 
#include <iostream>#include <string>using namespace std;​int main() {    string bikePrice = "100000";  // Price stored as text    int discount = 5000;          // Discount stored as a number​    // Uncommenting the following line will cause a compilation error    // string totalPrice = bikePrice + discount;​    return 0;}​