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Learn more about: Debug routines |
Debug routines |
04/10/2018 |
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cb4d2664-10f3-42f7-a516-595558075471 |
The debug version of the C runtime library supplies many diagnostic services that make debugging programs easier and allow developers to:
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Step directly into run-time functions during debugging
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Resolve assertions, errors, and exceptions
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Trace heap allocations and prevent memory leaks
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Report debug messages to the user
To use these routines, the _DEBUG flag must be defined. All of these routines do nothing in a retail build of an application. For more information on how to use the new debug routines, see CRT Debugging Techniques.
| Routine | Use |
|---|---|
_ASSERT |
Evaluate an expression and generates a debug report when the result is FALSE |
_ASSERTE |
Similar to _ASSERT, but includes the failed expression in the generated report |
_CrtCheckMemory |
Confirm the integrity of the memory blocks allocated on the debug heap |
_CrtDbgBreak |
Sets a break point. |
_CrtDbgReport, _CrtDbgReportW |
Generate a debug report with a user message and send the report to three possible destinations |
_CrtDoForAllClientObjects |
Call an application-supplied function for all _CLIENT_BLOCK types on the heap |
_CrtDumpMemoryLeaks |
Dump all of the memory blocks on the debug heap when a significant memory leak has occurred |
_CrtIsMemoryBlock |
Verify that a specified memory block is located within the local heap and that it has a valid debug heap block type identifier |
_CrtIsValidHeapPointer |
Verifies that a specified pointer is in the local heap |
_CrtIsValidPointer |
Verify that a specified memory range is valid for reading and writing |
_CrtMemCheckpoint |
Obtain the current state of the debug heap and store it in an application-supplied _CrtMemState structure |
_CrtMemDifference |
Compare two memory states for significant differences and return the results |
_CrtMemDumpAllObjectsSince |
Dump information about objects on the heap since a specified checkpoint was taken or from the start of program execution |
_CrtMemDumpStatistics |
Dump the debug header information for a specified memory state in a user-readable form |
_CrtReportBlockType |
Returns the block type/subtype associated with a given debug heap block pointer. |
_CrtSetAllocHook |
Install a client-defined allocation function by hooking it into the C run-time debug memory allocation process |
_CrtSetBreakAlloc |
Set a breakpoint on a specified object allocation order number |
_CrtSetDbgFlag |
Retrieve or modify the state of the _crtDbgFlag flag to control the allocation behavior of the debug heap manager |
_CrtSetDumpClient |
Install an application-defined function that is called every time a debug dump function is called to dump _CLIENT_BLOCK type memory blocks |
_CrtSetReportFile |
Identify the file or stream to be used as a destination for a specific report type by _CrtDbgReport |
_CrtSetReportHook |
Install a client-defined reporting function by hooking it into the C run-time debug reporting process |
_CrtSetReportHook2, _CrtSetReportHookW2 |
Installs or uninstalls a client-defined reporting function by hooking it into the C run-time debug reporting process. |
_CrtSetReportMode |
Specify the general destination(s) for a specific report type generated by _CrtDbgReport |
| _RPT[0,1,2,3,4] | Track the application's progress by generating a debug report by calling _CrtDbgReport with a format string and a variable number of arguments. Provides no source file and line number information. |
| _RPTF[0,1,2,3,4] | Similar to the _RPTn macros, but provides the source file name and line number where the report request originated |
_calloc_dbg |
Allocate a specified number of memory blocks on the heap with additional space for a debugging header and overwrite buffers |
_expand_dbg |
Resize a specified block of memory on the heap by expanding or contracting the block |
_free_dbg |
Free a block of memory on the heap |
_fullpath_dbg, _wfullpath_dbg |
Create an absolute or full path name for the specified relative path name, using _malloc_dbg to allocate memory. |
_getcwd_dbg, _wgetcwd_dbg |
Get the current working directory, using _malloc_dbg to allocate memory. |
_malloc_dbg |
Allocate a block of memory on the heap with additional space for a debugging header and overwrite buffers |
_msize_dbg |
Calculate the size of a block of memory on the heap |
_realloc_dbg |
Reallocate a specified block of memory on the heap by moving and/or resizing the block |
_strdup_dbg, _wcsdup_dbg |
Duplicates a string, using _malloc_dbg to allocate memory. |
_tempnam_dbg, _wtempnam_dbg |
Generate names you can use to create temporary files, using _malloc_dbg to allocate memory. |
The debugger can be used to step through the source code for most of the C runtime routines during the debugging process. However, Microsoft considers some technology to be proprietary and, therefore, does not provide the source code for a subset of these routines. Most of these routines belong to either the exception handling or floating-point processing groups, but a few others are included as well. The following table lists these routines.
:::row:::
:::column span="":::
acos
acosh
asin
asinh
atan, atan2
atanh
Bessel functions
_cabs
ceil
_chgsign
_clear87, _clearfp
_control87, _controlfp
:::column-end:::
:::column span="":::
copysign
cos
cosh
Exp
fabs
_finite
floor
fmod
_fpclass
_fpieee_flt
_fpreset
frexp
:::column-end:::
:::column span="":::
_hypot
_isnan
ldexp
log
_logb
log10
longjmp
_matherr
modf
_nextafter
pow
printf_s
:::column-end:::
:::column span="":::
printf
_scalb
scanf_s
scanf
setjmp
sin
sinh
sqrt
_status87, _statusfp
tan
tanh
:::column-end:::
:::row-end:::
Although source code is available for most of the printf and scanf routines, they make an internal call to another routine for which source code is not provided.
Some C run-time functions and C++ operators behave differently when called from a debug build of an application. (Note that a debug build of an application can be done by either defining the _DEBUG flag or by linking with a debug version of the C run-time library.) The behavioral differences usually consist of extra features or information provided by the routine to support the debugging process. The following table lists these routines.
:::row:::
:::column span="":::
C abort routine
:::column-end:::
:::column span="":::
C assert routine
:::column-end:::
:::column span="":::
C++ delete operator
:::column-end:::
:::column span="":::
C++ new operator
:::column-end:::
:::row-end:::
Universal C runtime routines by category
Run-Time Error Checking