


Is the Memory Address of a String Literal Consistent Across Translation Units in C and C ?
Nov 04, 2024 am 08:34 AMString Literal Address Across Translation Units
In C and C , programmers often use string literals for various purposes. A common question arises: is it reliable to assume that the same string literal in different translation units will have the same memory address?
C/C Standard
The C99 and C draft standards specifically leave this topic unspecified. Section 6.4.5 of the C99 draft standard states that "It is unspecified whether these arrays [string literals] are distinct provided their elements have the appropriate values." This means that the compiler is free to decide whether to pool string literals or not.
Compiler Implementations
In practice, different compilers have different behaviors regarding string literal pooling.
- GCC: Supports string literal pooling across compilation units with the -fmerge-constants flag. This behavior can be disabled with -fno-merge-constants.
- Visual Studio: Includes an option (/GF) for string literal pooling.
- Other compilers: May or may not support string literal pooling, and it is implementation-specific.
Rationale for Lack of Requirement
The rationale for not requiring string literals to be pooled in the C standard is due to the diversity of compilers and runtime environments at the time. Some implementations stored string literals in ROM, while others stored them in writable data sections. To ensure portability, it was deemed best to not mandate any specific behavior.
Practical Considerations
In general, it is not portable to rely on string literals having the same memory address across translation units. However, within the same translation unit, the behavior is more likely to be consistent, as the compiler has more control over optimizations.
Conclusion
The memory address of a string literal is an implementation detail and cannot be relied upon to remain consistent across translation units. It is important to be aware of this fact and write code that is independent of such implementation details.
The above is the detailed content of Is the Memory Address of a String Literal Consistent Across Translation Units in C and C ?. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

Yes, function overloading is a polymorphic form in C, specifically compile-time polymorphism. 1. Function overload allows multiple functions with the same name but different parameter lists. 2. The compiler decides which function to call at compile time based on the provided parameters. 3. Unlike runtime polymorphism, function overloading has no extra overhead at runtime, and is simple to implement but less flexible.

C has two main polymorphic types: compile-time polymorphism and run-time polymorphism. 1. Compilation-time polymorphism is implemented through function overloading and templates, providing high efficiency but may lead to code bloating. 2. Runtime polymorphism is implemented through virtual functions and inheritance, providing flexibility but performance overhead.

Yes, polymorphisms in C are very useful. 1) It provides flexibility to allow easy addition of new types; 2) promotes code reuse and reduces duplication; 3) simplifies maintenance, making the code easier to expand and adapt to changes. Despite performance and memory management challenges, its advantages are particularly significant in complex systems.

C destructorscanleadtoseveralcommonerrors.Toavoidthem:1)Preventdoubledeletionbysettingpointerstonullptrorusingsmartpointers.2)Handleexceptionsindestructorsbycatchingandloggingthem.3)Usevirtualdestructorsinbaseclassesforproperpolymorphicdestruction.4

Polymorphisms in C are divided into runtime polymorphisms and compile-time polymorphisms. 1. Runtime polymorphism is implemented through virtual functions, allowing the correct method to be called dynamically at runtime. 2. Compilation-time polymorphism is implemented through function overloading and templates, providing higher performance and flexibility.

People who study Python transfer to C The most direct confusion is: Why can't you write like Python? Because C, although the syntax is more complex, provides underlying control capabilities and performance advantages. 1. In terms of syntax structure, C uses curly braces {} instead of indentation to organize code blocks, and variable types must be explicitly declared; 2. In terms of type system and memory management, C does not have an automatic garbage collection mechanism, and needs to manually manage memory and pay attention to releasing resources. RAII technology can assist resource management; 3. In functions and class definitions, C needs to explicitly access modifiers, constructors and destructors, and supports advanced functions such as operator overloading; 4. In terms of standard libraries, STL provides powerful containers and algorithms, but needs to adapt to generic programming ideas; 5

C polymorphismincludescompile-time,runtime,andtemplatepolymorphism.1)Compile-timepolymorphismusesfunctionandoperatoroverloadingforefficiency.2)Runtimepolymorphismemploysvirtualfunctionsforflexibility.3)Templatepolymorphismenablesgenericprogrammingfo

C polymorphismisuniqueduetoitscombinationofcompile-timeandruntimepolymorphism,allowingforbothefficiencyandflexibility.Toharnessitspowerstylishly:1)Usesmartpointerslikestd::unique_ptrformemorymanagement,2)Ensurebaseclasseshavevirtualdestructors,3)Emp
