TAILIEUCHUNG - Thinking in C plus plu (P5)

Tham khảo tài liệu 'thinking in c plus plu (p5)', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | allows you to make this type conversion explicit or to force it when it wouldn t normally happen. To perform a cast put the desired data type including all modifiers inside parentheses to the left of the value. This value can be a variable a constant the value produced by an expression or the return value of a function. Here s an example C03 int main int b 200 unsigned long a unsigned long int b Casting is powerful but it can cause headaches because in some situations it forces the compiler to treat data as if it were for instance larger than it really is so it will occupy more space in memory this can trample over other data. This usually occurs when casting pointers not when making simple casts like the one shown above. C has an additional casting syntax which follows the function call syntax. This syntax puts the parentheses around the argument like a function call rather than around the data type C03 int main float a float 200 This is equivalent to float b float 200 Of course in the case above you wouldn t really need a cast you could just say 200f in effect that s typically what the compiler will do for the above expression . Casts are generally used instead with variables rather than constants. 180 Thinking in C C explicit casts Casts should be used carefully because what you are actually doing is saying to the compiler Forget type checking - treat it as this other type instead. That is you re introducing a hole in the C type system and preventing the compiler from telling you that you re doing something wrong with a type. What s worse the compiler believes you implicitly and doesn t perform any other checking to catch errors. Once you start casting you open yourself up for all kinds of problems. In fact any program that uses a lot of casts should be viewed with suspicion no matter how much you are told it simply must be done that way. In general casts should be few and isolated to the solution of very .

• Kỹ thuật lập trình
• lập trình với Cplus plus
• giáo trình C plus plus
• Lập trình hướng đối tượng với C plus plus
• Mẹo lập trình
• thủ thuật lập trình