C++ String Built-in Functions

1. Capacity Functions

Function	Description
s.size()	Returns the size (length) of the string.
s.max_size()	Returns the maximum size a string can hold.
s.capacity()	Returns the current capacity of the string.
s.clear()	Removes all characters from the string.
s.empty()	Returns true if the string is empty, otherwise false.
s.resize(n)	Changes the size of the string to n.

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2. Element Access Functions

Function	Description
s[i]	Accesses the character at index i.
s.at(i)	Accesses the character at index i with bounds checking.
s.front()	Returns the first character of the string.
s.back()	Returns the last character of the string.

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3. Modifier Functions

Function	Description
s += str	Appends another string to the current string.
s.append(str)	Appends another string.
s.push_back(ch)	Adds a character at the end of the string.
s.pop_back()	Removes the last character of the string.
s = str	Assigns a new string.
s.assign(str)	Assigns a new string.
s.erase(pos, len)	Removes characters from the string.
s.replace(pos, len, str)	Replaces a portion of the string.
s.insert(pos, str)	Inserts a string at a specific position.

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4. Iterator Functions

Function	Description
s.begin()	Returns an iterator pointing to the first character.
s.end()	Returns an iterator pointing to the position after the last character.

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Example

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

int main() {
    string s = "Hello";

    cout << s.size() << endl;      // 5
    cout << s.front() << endl;     // H
    cout << s.back() << endl;      // o

    s.push_back('!');
    cout << s << endl;             // Hello!

    s.pop_back();
    cout << s << endl;             // Hello

    return 0;
}