String concatenation

Learn to join text with the + operator and append.

Concatenating with +

To put two std::string values side by side you use the + operator. For example std::string fullName = firstName + " " + lastName; joins the first name, a space and the last name into one string.

You can add a string to a string, or a string to a char* literal (double-quoted text). Two char* literals cannot be added directly; you must first convert one to std::string. The result is always a new std::string.

The append method

To add a piece to an existing string you can use the append method: name.append(" Brown");. This works like the + operator, but it modifies the string in place instead of creating a new one.

append is especially efficient when you add pieces repeatedly in a loop; it does not build a new string each time. To print the result, you can use std::cout << name; as usual.

Exercise Combine first and last name

The lines that set firstName to "Alex" and lastName to "Brown" are already in place. Now declare fullName by concatenating firstName + " " + lastName and print it with std::cout.

Show example solution

#include <iostream>
#include <string>

int main() {
    std::string firstName = "Alex";
    std::string lastName = "Brown";
    std::string fullName = firstName + " " + lastName;
    std::cout << fullName << std::endl;
    return 0;
}

Test yourself

Write the concatenation operator

std::string fullName = firstName____ " " + lastName;

Show answer

std::string fullName = firstName+ " " + lastName;

What is the result of std::string s = "A"; s.append("B");?
```
std::string s = "A";
s.append("B");
```
- s = "A"
- s = "B"
- s = "A B"
- s = "AB"
Show answer

s = "AB" — append adds "B" at the end of "A"; the result is "AB".
Match each operator/method to its job

+

Joins two strings
.append(x)

Appends at the end
.size()

Returns the length
<<

Writes to a stream

Next lesson: String length

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