How Can I Access and Print Elements of a std::vector in GDB?

Accessing Vector Elements in GDB

When debugging C code, it's crucial to examine the contents of data structures. For a std::vector, this can be especially challenging in GDB.

Addressing Vector Elements

In GCC 4.1.2, the internal array of a std::vector can be accessed via the pointer:

myVector._M_impl._M_start

where myVector is the name of the vector.

Printing Vector Elements

To print the entirety of a std::vector<int> named myVector, execute the following GDB command:

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

This command prints all elements in the vector. To print only the first N elements, use:

print *(myVector._M_impl._M_start)@N

Explanation

The asterisk (*) is used to dereference the _M_start pointer, which points to the beginning of the internal array. The @ symbol specifies the number of elements to print.

This method is version-dependent and may vary with different compiler versions.

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