Found a total of 10000 related content
C undefined behavior example
Article Introduction：Accessing out-of-bound array elements is undefined behavior, which may cause crash or optimization exception; 2. Reading its value with uninitialized local variables is undefined behavior, and the results are unpredictable; 3. Dereference of null pointers is undefined behavior, and even conditional judgments may be optimized, resulting in logical errors; 4. Overflow of signed integers is undefined behavior, and the compiler can perform radical optimization based on this; 5. Returning references or pointers to local variables lead to dangling references, which generate undefined behavior when used; undefined behavior is dangerous because the program may seem to run normally but crash in different environments or optimizations, and is prone to cause security vulnerabilities. It should be detected through modern C tools, compilation warnings, static analysis and sanitizer such as -fsanitize=undefined
2025-07-24
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528
Why is the PHP fileinfo function undefined?
Article Introduction：Troubleshooting PHP Fileinfo Function Undefined ErrorIn PHP, encountering the "finfo" class or "finfo_open" function as undefined can be...
2024-11-10
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760
How to Detect Undefined Variables in JavaScript?
Article Introduction：Detecting Undefined Variables in JavaScriptDetermining whether a variable is defined or undefined is crucial in JavaScript coding. A common error...
2024-11-01
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568
How to Identify Undefined Variables in PHP?
Article Introduction：Identifying Undefined Variables in PHPIn PHP, the isset() function allows you to check if a variable has been set, but it does not distinguish between undefined and null values. To explicitly check for undefined variables, similar to the JavaScript s
2024-10-19
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590
Undefined Vs Not defined
Article Introduction：First, we need to understand the JavaScript Code Execution process, which consists of two phases: the Memory Creation Phase and the Code Execution Phase. Both 'undefined' and 'not defined' are related to memory space.
undefined
In the Memory Creati
2024-11-23
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474
Is `i = i` Always Undefined Behavior in C ?
Article Introduction：undefined Behavior and Sequence Points RevisitedUndefined Behavior for Built-in TypesIn a previous installment, "Undefined Behavior and Sequence...
2024-12-07
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