Javatpoint Logo
Javatpoint Logo

std::string::append vs std::string::push_back() vs Operator += in C++

String manipulation is a rather frequent operation in C++ and it is important to select an appropriate concatenation way to guarantee efficiency and good readable code. This blog post will explore three popular methods for concatenating strings in C++: append, push_back, or += operator for std::string type.

What is std::string::append()?

The std::string::append() is a good and flexible means of appending strings. Therefore, the end of a string can be used to append substrings or entire strings onto the current string. This method takes two parameters: source string and length of characters to add.


Let's take an example to illustrate the use of std::string::append() function in C++:


Hello, world!

What is Std::string::push_back()?

On the other hand, the std::string::push_back() approach is especially designed for appending a single character to the quit of a string. While reputedly much less versatile than std::string::append(), this approach shines in situations wherein building a string character via character is essential.


Let's take an example to illustrate the use of std::string::push_back() function in C++:


Hello, World!

Operator +=

The += operator gives a concise and broadly used alternative for string concatenation. It essentially acts as a shorthand for the std::string::append() approach. The left-hand aspect string is modified with the aid of appending the characters of the right-hand side string.


Let's take an example to illustrate the use of += operator in C++:


Hello, world!

Performance Comparison

When it involves overall performance, the selection among those techniques can drastically impact the performance of the code. Let's examine the time complexities of these strategies:

  • std::string::append(): O(n) - Linear time complexity, wherein 'n' is the duration of the appended string.
  • Std::string::push_back(): O(1) - Constant time complexity, because it appends only one person at a time.
  • Operator +=: O(n) - Linear time complexity, similar to std::string::append().

In eventualities where we're concatenating entire strings or large substrings, std::string::append() or Operator += is probably extra efficient, as they take care of a couple of characters right now. On the opposite hand, if we are constructing a string individual, in particular in loops or dynamic eventualities, std::string::push_back() can be more appropriate due to its regular time complexity.

Difference between std::string::append, std::string::push_back(), and Operator += in C++

Method Description Use Case Time Complexity
std::string::append() Appends a portion of a string or another entire string. When concatenating multiple strings or substrings. O(n) - Linear
std::string::push_back() Appends a single character at the end of the string. Useful when building a string character by character. O(1) - Constant
Operator += Concatenates the right-hand side string to the left-hand side. A concise and commonly used method for string concatenation. O(n) - Linear


In the end, the selection of string concatenation strategies in C++ entails a nuanced assessment of exchange-offs among performance optimization and code clarity. The std::string::append() approach stands out for its versatility, excelling in eventualities where complete strings or substrings want to be concatenated efficiently. Its capacity to deal with more than one character immediately makes it properly-suited for responsibilities involving the concatenation of vast data.

On the alternative hand, std::string::push_back() demonstrates performance in person-by-using individual construction, specifically valuable in dynamic eventualities and loop iterations where steady time complexity is critical. Despite its simplicity, it shines in eventualities wherein strings are constructed incrementally, providing clarity and control over person characters.

The widely used += operator serves as a succinct opportunity, supplying stability among performance and readability. Its concise syntax simplifies code whilst handing over comparable overall performance to std::string::append(). In the stop, the selection rests on the codebase's unique desires, considering elements like the scale of concatenation operations and the dynamic nature of string construction. Striking the right stability guarantees that C++ code remains not only green but also maintainable, meeting the numerous necessities of different scenarios in software program improvement. With these issues, developers can make knowledgeable alternatives, contributing to the general effectiveness of their C++ code.

Youtube For Videos Join Our Youtube Channel: Join Now


Help Others, Please Share

facebook twitter pinterest

Learn Latest Tutorials


Trending Technologies

B.Tech / MCA