How to Print Vector Elements in C Using GDB?

Printing Vector Elements in C via GDB

When debugging C code in GDB, examining the contents of a std::vector can be challenging. For instance, consider a std::vector named myVector. How do we effectively print its elements?

In GCC 4.1.2, the solution involves accessing the vector's internal pointer, myVector._M_impl._M_start, which points to the array holding the vector's elements.

To print the entire vector, use:

print *(myVector._M_impl._M_start)@myVector.size()

To print only the first N elements, modify it to:

print *(myVector._M_impl._M_start)@N

Reasoning

This approach leverages the GDB command to print N elements of an array starting at a given pointer. In this case, the pointer is myVector._M_impl._M_start, and we specify the number of elements to print using myVector.size() or the desired count N.

While this approach is applicable to GCC 4.1.2, it might vary depending on your compiler version. So, for other versions, consulting the relevant documentation is recommended.

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