How to debug C++ programs using GDB?

Using GDB to debug C++ program involves: setting up GDB, using the -g option to compile the code, generating debugging information, starting GDB and loading the program, debugging using the following commands: run: run the program break: set a breakpoint next: execute the next line of code step: step by step Line execution code print: Print the value of the variable bt: View the call stack quit: Exit GDB

How to use GDB to debug C++ programs

Introduction

GDB (GNU Debugger) is a powerful tool for debugging C++ programs. It allows programmers to inspect the status of a program at runtime, set breakpoints, and execute code line by line.

Set up GDB

1. Install GDB. Ubuntu users can use the following command:

   sudo apt-get install gdb

2. Compile a C++ program to generate debugging information. Use the following g++ options:

   g++ -g -o program program.cpp

Start GDB

1. Run GDB and load the program:

   gdb program

2. Use the following command to Attach to the running program:

   attach pid

Basic debugging commands

• run Run the program
• break Set breakpoint
• next Execute the next line of code
• step Execute the code line by line
• print Print the value of the variable
• bt View the call stack
• quit Exit GDB

Practical case

The following is an example of a simple C++ program, which uses GDB to debug:

#include <iostream>

using namespace std;

int main() {
  int a = 10;
  int b = 20;
  int c = a + b;
  cout << "c = " << c << endl;
  return 0;
}

Debugging steps

1. Compile the program and generate debugging information:

   g++ -g -o program program.cpp

2. Start GDB and load the program:

   gdb program

3. Set a breakpoint:

   break 11

4. Run the program:

   run

5. The program will stop at line 11:

6. int c = a + b;

7. Check the value of the variable:

   print c

8. One by one Line execution code:

   next

9. Exit GDB:

   quit

Conclusion

GDB is a powerful Tools for debugging C++ programs. By following these steps, you can use GDB effectively to find and fix bugs in your programs.

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