What does the "at" operator do in C++? For example, string.at or word.at

Question

// Iterate(loop/repetition) over the word
for(int i = 0; i < (int)word.size(); i++ ){
    // Get a character
    char ch = word.at(i);

    // If the character matches the character we're looking for
    if(searchCh == ch){

        // Increment a counter
        counter++; // counter = counter + 1

What does word.at(i) mean in the operator or what does the "at" operator do in C++? For example, string.at or word.at

read this: http://en.cppreference.com/w/cpp/string/basic_string/at — billz, Jul 30 '15 at 23:10
Okay thanks everyone. I just googled it and understood it clearly. It wasn't popping up on google because I thought it was an operator. — Giorgio, Jul 30 '15 at 23:18
Why not just test it like: "if (searchChar==word[i])" ? and change the conditional expression to "i — Donald, Jul 30 '15 at 23:21
@Donald Saving values in local variables is a very common practice, making debugging easy, especially in complex DS, where you may need to see `this->data->registered_entries[n].data.name.c_str()`. — Mateusz Grzejek, Jul 30 '15 at 23:23
@Barmar: Please do not answer questions in the comment section. — Lightness Races in Orbit, Jul 30 '15 at 23:40

ex-bart · Answer 1 · 2015-07-31T13:13:23.480

2

You probably mean "how is word.at(i) different from word[i]"?

word.at(i) generally checks whether i is in range and throws an exception if not. word[i] just is undefined behaviour if i is out of range.

Also, with word[word.size()] you can access the implicit trailing '\0'-byte, but for word.at(word.size()) the index is out of range.

edited Jul 31 '15 at 13:13

answered Jul 30 '15 at 23:24

ex-bart

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score 0 · Answer 2 · edited Mar 21 '18 at 09:27

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at() is a member function in C++. s.at() returns the letter at position i in the string. But if the position is not in the range, it throws an exception.

edited Mar 21 '18 at 09:27

Stephen Kennedy

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answered Mar 21 '18 at 09:06

Siddhi jaju

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What does the "at" operator do in C++? For example, string.at or word.at

2 Answers2