Computer science is the study of the theoretical foundations of information and computation, and of practical techniques for their implementation and application in computer systems.... , weak typing (a.k.a. loose typing) is a property attributed to the type system
Type system
In computer science, a type system may be defined as "a tractable syntactic method for proving the absence of certain program behaviors by classifying phrases according to the kinds of values they compute.".... s of some programming language
Programming language
A programming language is a machine-readable artificial language designed to express computations that can be performed by a machine, particularly a computer.... s. It is the opposite of strong typing, and consequently the term weak typing has as many different meanings as strong typing does (see strong typing for a list and detailed discussion).
One of the more common definitions states that weakly-typed programming languages are those that support either implicit type conversion
Type conversion
In computer science, type conversion or typecasting refers to changing an entity of one data type into another. This is done to take advantage of certain features of type hierarchies.... (nearly all languages support at least one implicit type conversion), ad-hoc polymorphism (also known as overloading) or both.
Computer science is the study of the theoretical foundations of information and computation, and of practical techniques for their implementation and application in computer systems.... , weak typing (a.k.a. loose typing) is a property attributed to the type system
Type system
In computer science, a type system may be defined as "a tractable syntactic method for proving the absence of certain program behaviors by classifying phrases according to the kinds of values they compute.".... s of some programming language
Programming language
A programming language is a machine-readable artificial language designed to express computations that can be performed by a machine, particularly a computer.... s. It is the opposite of strong typing, and consequently the term weak typing has as many different meanings as strong typing does (see strong typing for a list and detailed discussion).
One of the more common definitions states that weakly-typed programming languages are those that support either implicit type conversion
Type conversion
In computer science, type conversion or typecasting refers to changing an entity of one data type into another. This is done to take advantage of certain features of type hierarchies.... (nearly all languages support at least one implicit type conversion), ad-hoc polymorphism (also known as overloading) or both. These less restrictive usage rules can give the impression that strict adherence to typing rules is less important than in strongly-typed languages and hence that the type system is "weaker". However, such languages usually have restrictions on what programmers can do with value
Value (computer science)
In computer science, a value is a sequence of bits that is interpreted according to some data type. It is possible for the same sequence of bits to have different values, depending on the type used to interpret its meaning.... s of a given type; thus it is possible for a weakly-typed language to be type safe
Type safety
In computer science, type safety is a property of some programming languages that is defined differently by different communities, but most definitions involve the use of a type system to prevent certain erroneous or undesirable program behavior .... . Moreover, weakly-typed languages may be statically typed, in which case overloading is resolved statically and type conversion operations are inserted by the compiler, or dynamically typed, in which case everything is resolved at run time.
The advantage claimed of weak typing is that it requires less effort on the part of the programmer than strong typing, because the compiler
Compiler
A compiler is a computer program that transforms source code written in a programming language into another computer language . The most common reason for wanting to transform source code is to create an executable program.... or interpreter implicitly performs certain kinds of conversions. However, one claimed disadvantage is that weakly typed programming systems catch fewer errors at compile time and some of these might still remain after testing has been completed. Two commonly used languages that support many kinds of implicit conversion are C
C (programming language)
C is a general-purpose computer programming language originally developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories to implement the Unix operating system.... and C++
C++
C++ is a general-purpose programming language. It is regarded as a middle-level language, as it comprises a combination of both high-level programming language and low-level programming language language features.... , and it is sometimes claimed that these are weakly typed languages. However, others argue that these languages place enough restrictions on how operands of different types can be mixed, that the two should be regarded as strongly typed languages.
C++ places more restrictions on the handling of enumerated types than C:
enum animal ;
animal a = CAT; /* The enum keyword here is optional in C++ */
animal b = 1; /* This is an error in C++ */
