[ fromfile: memoryaccess.xml id: memoryaccess ]

Direct manipulation of memory entails some serious risks and requires good practices and thorough testing to avoid serious errors. Improper use of pointers and dynamic memory can cause program crashes that result from heap corruption and memory leaks. Heap corruption is especially difficult to debug because it generally leads to segmentation faults that halt the program at a point in the code that may be far from the point at which the heap became corrupted.

Both Qt and Standard Library container classes permit the safe use of dynamic memory without adversely affecting performance.^[117] Arrays implement most container classes but are hidden from client code. The safety factors come from the careful design of each container API so that actions that might produce memory problems are not permitted.

Qt offers many containers, ranging from high-level template classes such as the ones discussed in Section 6.8, to low-level containers such as QBitArray and QByteArray.

Generally, when writing applications that reuse those containers, it is easy to avoid the use of arrays entirely. When Qt is not available, or when you need to write an interface to C code, you may need to use arrays and pointers and work directly with allocated memory.

Modern software often has colorful graphics and sound that require rapid processing for proper execution. That generally means that heavy use must be made of dynamic memory. Vast quantities of memory and secondary storage are available on the typical computing device – quantities that were unimaginable just a few years ago. But graphics, animation, and sound all require substantial amounts of memory that must be handled carefully and efficiently. That is why we focus on the proper management of memory resources and on the dire consequences of mismanagement.