C++ 23 <stacktrace> – Header

Imagine you’re on an adventure, exploring a vast and dense forest. Along the way, you encounter challenges that might leave you feeling lost or confused. In such situations, a map or compass would be invaluable tools to guide you back on track.

Similarly, in the world of programming, stack traces serve as a map of sorts, helping you navigate the complex pathways of your code. They provide a detailed record of the function calls that led to a particular point in your program’s execution, much like a traveler tracing their footsteps on a map.

What is Stacktrace?

The stack trace is an object in programming that keeps track of the called functions till a particular point in the program. It keeps a log of the stack frames currently present in the function call stack of the program.

Stacktraces not only help in debugging errors, but they also help in performance analysis and code optimization. By examining the execution time of each function in a stack trace, you can identify performance bottlenecks and optimize your code accordingly.

Stacktrace in C++

The <stacktrace> header being introduced in C++ 23 provides a powerful set of tools for capturing, manipulating, and interpreting stack traces. It defines two classes:

1. std::stacktrace_entry
2. std::stacktrace

Let’s discuss both of them one by one.

1. std::stacktace_entry Class

In C++, the std::stacktrace_entry class represents the record of a single stack frame in the function call stack. It provides three member functions to query the information about the particular stacktrace entry:

std::stacktrace_entry Member Function in C++

S. No.	Function	Operation
1	description()	This function returns a string containing the description of the stack entry if there is any.
2	source_file()	It returns the name of the source file.
3	source_line()	It returns the number of lines at which the stack entry was created i.e. the corresponding function was called.

The stacktrace_entry can either be empty or contain information about the stacktrace entries. We don’t generally use the stacktrace_entry class directly but instead, it is used with the stacktrace entry class.

2. std::stacktrace Class

The std::stacktrace class in C++ is the actual class that keeps the records of the stack frames along with their sequence of execution.

Note: The name stacktrace is actually an alias of the class named basic_stacktrace.

Stacktrace Function in C++

The stacktrace also contains the member functions that are used to provide various basic functionalities:

S. No.	Function	Operation
1	begin()	Returns the iterator to the first element.
2	end()	Returns the iterator to the imaginary element present after the last element.
3	empty()	Returns true if the stacktrace is empty. Otherwise false.
4	size()	Returns the number of stacktrace entries present in the stacktrace object.
5	at()	Returns the element present at the given index.
6	current()	It is a static member function that is used to return the stacktrace object at the point of calling.

How to use stacktrace in C++?

We can use the stacktrace in C++ as shown:

1. Stacktrace Object Declaration

We first declare a stacktrace object using the syntax shown below:

std::stacktrace name;

2. Stacktrace Object Initialization

We initialize the newly created stacktrace object using the stacktrace::current() function.

std::stacktrace st = std::stacktrace::current()

Example of Stacktrace

C++

// C++ program to illustrate the use of stacktrace
#include <iostream>
#include <stacktrace>
#include <string>

using namespace std;

// dummy function
void foo()
{
    // creating and initializing stacktrace object
    stacktrace st = stacktrace::current();

    // printing stacktrace
    cout << to_string(st);
}

// driver code
int main()
{

    foo();

    return 0;
}

   0# foo() at /app/stacktrace.cpp:12
   1#
   2#      at /app/example.cpp:22
   3#      at :0
   4#      at :0
   5# 

Explanation:

• Stream Insertion Operators for Stack Trace Printing: Employ the stream insertion operators (<<) to directly print the entire stack trace to the console, providing a concise representation of the execution flow.
• Console-Based Stack Trace Printing: Utilize the std::cout object to print the captured stack trace to the console, conveniently displaying the call stack information.
• Converting Stack Trace to String: Leverage the std::to_string() function to convert the stack trace object into a string representation, enabling further manipulation and storage.

Conclusion

By capturing and manipulating stack traces, developers can pinpoint the root causes of errors, identify performance bottlenecks, and refine their code for enhanced efficiency. The <stacktrace> header emerges as an indispensable tool for modern software development, empowering programmers to craft robust and efficient software with greater confidence.

FAQs on C++ Stacktrace

1. What is the purpose of the <stacktrace> header in C++23?

Answer:

The <stacktrace> header provides a set of tools for capturing, manipulating, and interpreting stack traces in C++23. Stack traces are a record of the function calls that led to a particular point in a program’s execution. They can be used for debugging, error handling, performance analysis, and other purposes.

2. What is a stacktrace_entry?

Answer:

A stack trace entry is a representation of a single frame in the execution stack. Each stack trace entry contains information about the function that was called, the source file where the function’s code is located, and the line number where the function call occurred.

3. How can I capture the current execution stack?

Answer:

The std::stacktrace::current() function can be used to capture the current execution stack and store it in a std::stacktrace object.

4. How can I print a stacktrace?

Answer:

A stacktrace can be printed to the console using the stream insertion operator (<<). For example, the following code prints the current execution stack to the console:

std::stacktrace st = std::stacktrace::current();     
std::cout<< st << std::end;

5. How can I compare two stack trace entries?

Answer:

The == and <=> operators can be used to compare two stack trace entries. The == operator returns true if the two entries represent the same execution point. The <=> operator returns -1 if the first entry occurs before the second entry, 0 if the two entries are equal, and 1 if the first entry occurs after the second entry.

7. What are some practical applications of stack traces?

Answer:

Stack traces can be used for a variety of purposes, including:

• Debugging errors
• Identifying performance bottlenecks
• Optimizing code
• Understanding the execution flow of a program