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Expressions
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This section contains C++ Expression topics.

Topics

Name | Description
Expressions (C++) | An expression is a sequence of operators, operands, and punctuators that specifies a computation. The formal syntax, listed in CodeGear C++ expressions, indicates that expressions are defined recursively: subexpressions can be nested without formal limit. (However, the compiler will report an out-of-memory error if it can't compile an expression that is too complex.) Note: CodeGear C++ expressions show how identifiers and operators are combined to form grammatically legal "phrases." Expressions are evaluated according to certain conversion, grouping, associativity, and precedence rules that depend on the operators used, the presence of parentheses, and the data types of the operands. The standard... more
Precedence Of Operators | There are 16 precedence categories, some of which contain only one operator. Operators in the same category have equal precedence with each other. Where duplicates of operators appear in the table, the first occurrence is unary, the second binary. Each category has an associativity rule: left to right, or right to left. In the absence of parentheses, these rules resolve the grouping of expressions with operators of equal precedence. The precedence of each operator in the following table is indicated by its order in the table. The first category (on the first line) has the highest precedence. Operators on the... more
Expressions And C++ | C++ allows the overloading of certain standard C operators, as explained in Overloading Operator Functions. An overloaded operator is defined to behave in a special way when applied to expressions of class type. For instance, the equality operator == might be defined in class complex to test the equality of two complex numbers without changing its normal usage with non-class data types. An overloaded operator is implemented as a function; this function determines the operand type, lvalue, and evaluation order to be applied when the overloaded operator is used. However, overloading cannot change the precedence of an operator. Similarly, C++... more
Evaluation Order | The order in which the compiler evaluates the operands of an expression is not specified, except where an operator specifically states otherwise. The compiler will try to rearrange the expression in order to improve the quality of the generated code. Care is therefore needed with expressions in which a value is modified more than once. In general, avoid writing expressions that both modify and use the value of the same object. For example, consider the expression
Errors And Overflows | Associativity and precedence of CodeGear C++ operators. summarizes the precedence and associativity of the operators. During the evaluation of an expression, the compiler can encounter many problematic situations, such as division by zero or out-of-range floating-point values. Integer overflow is ignored (C uses modulo 2n arithmetic on n-bit registers), but errors detected by math library functions can be handled by standard or user-defined routines.See _matherr and signal.

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