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[18] [19] The following example will cause undefined behavior in both C and C++. int f ( int i ) { return i ++ + i ++ ; /* undefined behavior: two unsequenced modifications to i */ } When modifying an object between two sequence points, reading the value of the object for any other purpose than determining the value to be stored is also ...
The detailed semantics of "the" ternary operator as well as its syntax differs significantly from language to language. A top level distinction from one language to another is whether the expressions permit side effects (as in most procedural languages) and whether the language provides short-circuit evaluation semantics, whereby only the selected expression is evaluated (most standard ...
Another example can be when dealing with structs. In the code snippet below, we have a struct student which contains some variables describing the information about a student. The function register_student leaks memory contents because it fails to fully initialize the members of struct student new_student .
In computer programming languages, an identifier is a lexical token (also called a symbol, but not to be confused with the symbol primitive data type) that names the language's entities. Some of the kinds of entities an identifier might denote include variables , data types , labels , subroutines , and modules .
32-bit compilers emit, respectively: _f _g@4 @h@4 In the stdcall and fastcall mangling schemes, the function is encoded as _name@X and @name@X respectively, where X is the number of bytes, in decimal, of the argument(s) in the parameter list (including those passed in registers, for fastcall).
The same is syntactically valid but has undefined behavior in C++, [8] however, where only the last-written member of a union is considered to have any value at all. For another example of type punning, see Stride of an array.
In the C and C++ languages, such non-portable constructs are generally grouped into three categories: Implementation-defined, unspecified, and undefined behavior. [3] The exact definition of unspecified behavior varies. In C++, it is defined as "behavior, for a well-formed program construct and correct data, that depends on the implementation."
Even though string literals should not be modified (this has undefined behavior in the C standard), in C they are of static char [] type, [11] [12] [13] so there is no implicit conversion in the original code (which points a char * at that array), while in C++ they are of static const char [] type, and thus there is an implicit conversion, so ...