It is applied in the fields of mathematics and programming. Function is the return type of this function.
The prototype statement of a function is a copy of its function header, and of course, a semicolon is added at the end of the statement. There are also subtle differences between function prototype statements and function headers. In the function prototype statement, each parameter in its parameter table is allowed to keep only the parameter type and omit the parameter name. If the parameter name is used, it is also allowed to be different from the corresponding parameter name in the function header.
Extended data:
Origin of function
The word "function" used in China's math book is translated. It was Li, an algebra expert in Qing Dynasty, who translated "function" into "function" when he translated Algebra (1859).
In ancient China, the word "Xin" and the word "Han" were universal and both had the meaning of "Han". Li's definition is: "every formula contains heaven, which is a function of heaven." In ancient China, four words were used to represent four different unknowns or variables: heaven, earth, people and things. The meaning of this definition is: "Whenever a formula contains the variable X, the formula is called a function of X."
So "function" means that the formula contains variables. The exact definition of the equation we are talking about refers to the equation with unknowns. However, in the early mathematical monograph "Nine Chapters Arithmetic" in China, the term equation refers to simultaneous linear equations with many unknowns, that is, the so-called linear equations.
Early concept
/kloc-in the 0/7th century, Galileo almost completely contained the concept of the relationship between functions or variables in his book Two New Sciences, and expressed the relationship between functions in words and proportional languages.
Descartes noticed the dependence of one variable on another in his analytic geometry around 1637, but he didn't realize the need to refine the concept of function at that time, so no one knew the general meaning of function until Newton and Leibniz established calculus in the late17th century, and most functions were studied as curves.
1673, Leibniz first used "function" to express "power". Later, he used this word to represent the geometric quantities of each point on the curve, such as abscissa, ordinate, tangent length and so on. At the same time, Newton used "flow" to express the relationship between variables in the discussion of calculus.
Baidu encyclopedia-function head