China
Africa
Explore chapters and articles related to this topic
IEC 61131-3 PLC programming languages (LD, FBD, SFC, ST, and IF)
Published in Raymond F. Gardner, Introduction to Plant Automation and Controls, 2020
Data types explicitly define the type of data to be used in a variable. Importantly, the data type defines the amount of memory in bits or bytes that must be set aside for storing the data, and each data type must be consistent with the operations it will undergo. In high-level programming languages, the data-type definitions are usually at the beginning of the program, but certainly before its variable is used. The data types correspond to the data used with the ladder-logic programming and consist of Integer numbers (Table 16.1)Floating point or real numbers (Table 16.2)Bit strings or logic information (Table 16.3)Strings or text (Table 16.4)Time values (Table 16.5)
Computer Programming
Published in Quamrul H. Mazumder, Introduction to Engineering, 2018
Every piece of data used in a computer program has a data type. The data type lets the computer know how much memory to allocate in storing that data, how to retrieve that data, and what operations can be performed with that data. The basic data types are as follows: An integer is any whole number and includes both positive and negative numbers.A real or floating-point number is a number with a decimal point.A boolean is a variable that can only be true (represented by a 1) or false (represented by a 0).A character is any single ASCII letter, number, or punctuation mark.An array is a list of related data all of the same type. It can be an array of any type listed above.A string is a special type of array composed of characters.
Introduction
Published in Randall L. Eubank, Ana Kupresanin, Statistical Computing in C++ and R, 2011
Randall L. Eubank, Ana Kupresanin
The syntax char* pf in the program says that pf is a pointer to char. This means it is a variable whose value is the address in memory that is occupied by a char variable. The address that has been assigned to pf is essentially that of the floating-point variable f which is obtained through the syntax &f. The problem is that &f is the address of a float while pf is expecting to receive the address of a char for its value. To make the transition from a float to a char address, a cast is used. In general, casting is the process of changing a variable from one data type into another in terms of how it is viewed by the compiler. C++ performs implicit casting in standard cases such as transforming an integer into a floating-point value and similar types of conversions. More generally, an explicit cast of a variable x to a new data type newType is accomplished with syntax of the form
Semantic typing of linked geoprocessing workflows
Published in International Journal of Digital Earth, 2018
Simon Scheider, Andrea Ballatore
Data types generally increase the transparency and clarity of a program, helping developers express expected inputs and outputs of computational resources, for example specifying whether a function input is a string, an integer, a raster dataset, or another function. The success of types in object-oriented programming lies in information hiding, which is a way of abstracting from implementation details (Guttag and Horning 1978). More specifically, type constraints allow for modularity, that is, they guide the choice of a function, and open slots can be filled with particular data of a corresponding type to obtain a desired result. A second advantage is constructivity, the ability to construct a variety of types by combining primitive ones. And a third advantage is type inference, that is, the possibility to use inference rules to automatically guess the types of output and input when applying an operation. In practice, this greatly reduces a programmer's efforts of documenting code.