Debug assertion failed! How can this problem be solved?

Debug one dayProgramThe following error suddenly exists:

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Microsoft Visual C ++ debug Library
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Debug assertion failed!

Program: I: \ Guangdong Unicom \ standard background program \ debug \ batchsave.exe
File: F: \ dd \ vctools \ crt_bld \ self_x86 \ CRT \ SRC \ strtol. c
Line: 94

Expression: nptr! = NULL

For information on how your program can cause an assertion
Failure, see the Visual C ++ documentation on asserts.

(Press retry to debug the Application)
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Abort (a) retry (r) Ignore (I)
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Tracking solution:

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1. Press F5 to run your program
2. Select "retry" when an error occurs"
3. Call the "call stack" window by pressing Alt + 7
4. Double-click the last defined function from top to bottom. The system will automatically display the file where the function is located, and the program will pause at the cursor. Generally, the error is near this. You can check the value of the variable.

A good debugging method.