Loops and Text

In this lesson, we'll look at iterating through text using loops in C++. Text (std::string) can be iterated in several ways in C++, because we can treat it as a sequence of characters.

Example: We want to go through each character in the word 'Test' and print it. We have several options:

// 1. Classic for loop
std::string word = "Test";
for(int i = 0; i < word.length(); i++) {
    std::cout << word[i] << std::endl;
}

// 2. Range-based for loop
for(char character : word) {
    std::cout << character << std::endl;
}

// 3. While loop
int i = 0;
while(i < word.length()) {
    std::cout << word[i] << std::endl;
    i++;
}

All these methods will print:

T
e
s
t

In C++, we can also use the at() method instead of square brackets for safer access to characters:

std::cout << word.at(i) << std::endl;

This method checks whether the index is not out of range of the string, and if it is, throws an exception instead of causing undefined behavior.