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C++ changes some C standard library functions to add additional overloaded functions with const type qualifiers, e.g. strchr returns char* in C, while C++ acts as if there were two overloaded functions const char *strchr(const char *) and a char *strchr(char *). In C23 generic selection will be used to make C's behaviour more similar to C++'s. [11]
There are several loopholes to pure const-correctness in C and C++. They exist primarily for compatibility with existing code. The first, which applies only to C++, is the use of const_cast, which allows the programmer to strip the const qualifier, making any object modifiable. The necessity of stripping the qualifier arises when using existing ...
C++14 allows the lookup to be done via an arbitrary type, so long as the comparison operator can compare that type with the actual key type. [16] This would allow a map from std::string to some value to compare against a const char* or any other type for which an operator< overload is available.
Even functions can be const in C++. The meaning here is that only a const function may be called for an object instantiated as const; a const function doesn't change any non-mutable data. C# has both a const and a readonly qualifier; its const is only for compile-time constants, while readonly can be used in constructors and other runtime ...
In C and C++ short, long, and long long types are required to be at least 16, 32, and 64 bits wide, respectively, but can be more. The int type is required to be at least as wide as short and at most as wide as long , and is typically the width of the word size on the processor of the machine (i.e. on a 32-bit machine it is often 32 bits wide ...
All comparison operators can be overloaded in C++. Since C++20 , the inequality operator is automatically generated if operator== is defined and all four relational operators are automatically generated if operator<=> is defined.
Examples are if, while, const, for and goto, which are keywords that happen to be common to both languages. In C, the basic built-in type names are also keywords (e.g., int, char) or combinations of keywords (e.g., unsigned char), while in Pascal the built-in type names are predefined normal identifiers.
char * pc [10]; // array of 10 elements of 'pointer to char' char (* pa)[10]; // pointer to a 10-element array of char The element pc requires ten blocks of memory of the size of pointer to char (usually 40 or 80 bytes on common platforms), but element pa is only one pointer (size 4 or 8 bytes), and the data it refers to is an array of ten ...