Concat(Stringstr): Concat the end of the specified string. X. concat (y); //You should get x.concat (y) = ab; This method does not affect the value of x.
Unless you write x = x.concat (y); y = x； //Assign the value of x to y; In addition, the printed results are mainly a and B. Not in the method of printing. Therefore, changing the positions of x and y has nothing to do with the printed results.
machine language
In a computer system, machine instructions specify specific actions of the computer system. When designing and manufacturing hardware, a series of computers use many instructions to specify the basic operations that the series of computers can perform, and these instructions together constitute the instruction system of the series of computers.
In the early days of computer application, programmers used the instruction system of machines to write computer application programs, which were called machine language programs. Programs written in machine language occupy less memory and have high execution efficiency, because each instruction corresponds to a specific basic action of the computer.