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How to use gdb in Ubuntu Terminal

Here's a practical, minimal guide for using GDB in Ubuntu terminal — from launching to setting breakpoints and navigating your code. 🧰 Step 1: Compile with Debug Symbols Use -g and disable optimizations ( -O0 preferred for debugging): bash Copy Edit g++ -g -O0 -o myprog myprog.cpp 🚀 Step 2: Launch GDB bash Copy Edit gdb ./myprog You'll see a (gdb) prompt. 🎯 Step 3: Set Breakpoints You can set breakpoints in three main ways : ✅ a. At a function gdb Copy Edit (gdb) break main ✅ b. At a specific file and line gdb Copy Edit (gdb) break myprog.cpp:42 ✅ c. At a method in a class gdb Copy Edit (gdb) break MyClass::doSomething If the symbol is mangled (C++), GDB usually demangles automatically, especially if compiled with -g . ▶️ Step 4: Run the Program gdb Copy Edit (gdb) run 🧭 Step 5: Navigate Command Meaning next or n Step over current line step or s Step into function call finish Run until current function returns continue or c Continue until...
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Notes Untutu GNU C/C++ compiler: How to configure gcc/g++ version in ubuntu?

 First erase the current update-alternatives setup for gcc and g++:

sudo update-alternatives --remove-all gcc 

sudo update-alternatives --remove-all g++

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Use sudo apt-get install gcc-<version1> gcc-<version2> g++-<version1> g++-<version2>; to install versions

eg sudo apt-get install gcc-11 gcc-13 g++-11 g++-13;

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Then run commands:

sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-<version1> 10

sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-<version2> 20

sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-<version1> 10

sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-<version2> 20

sudo update-alternatives --install /usr/bin/cc cc /usr/bin/gcc 30

sudo update-alternatives --set cc /usr/bin/gcc

sudo update-alternatives --install /usr/bin/c++ c++ /usr/bin/g++ 30

sudo update-alternatives --set c++ /usr/bin/g++

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Finally to configure default version usage use following commands

sudo update-alternatives --config gcc

sudo update-alternatives --config g++

--

Check version using command

gcc --version;

g++ --version;

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If you have any doubts, please let me know.

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