The usefulness of the "Hello World" programs shown in the previous section is quite questionable. We had to write several lines of code, compile them, and then execute the resulting program just to obtain a simple sentence written on the screen as result. It certainly would have been much faster to type the output sentence by ourselves. However, programming is not limited only to printing simple texts on the screen. In order to go a little further on and to become able to write programs that perform useful tasks that really save us work we need to introduce the concept of variable.Let us think that I ask you to retain the number 5 in your mental memory, and then I ask you to memorize also the number 2 at the same time. You have just stored two different values in your memory. Now, if I ask you to add 1 to the first number I said, you should be retaining the numbers 6 (that is 5+1) and 2 in your memory. Values that we could now -for example- subtract and obtain 4 as result.The whole process that you have just done with your mental memory is a simile of what a computer can do with two variables. The same process can be expressed in C++ with the following instruction set:a = 5;b = 2;a = a + 1;result = a - b;Obviously, this is a very simple example since we have only used two small integer values, but consider that your computer can store millions of numbers like these at the same time and conduct sophisticated mathematical operations with them.Therefore, we can define a variable as a portion of memory to store a determined value.Each variable needs an identifier that distinguishes it from the others. For example, in the previous code the variable identifiers were a, b and result, but we could have called the variables any names we wanted to invent, as long as they were valid identifiers.
C++
Topic: Variable
Explain about Variables Data Types ?
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Scope of variables
Explain about Initialization of variables ?
Explain about Variable Declaration in C++ ?
Explain about Variable Initialization in C++:
Explain about Initializing Local and Global Variables ?
Explain about Global Variables ?
Explain about Calculations and variables ?
Why global variables are evil ?
How to store letters in a variable?
declaring floating-point type variables
What are variable declaration in c++ syntax ?
Write a function using reference variables as arguments to swap the values of a pair of integers?
How to access change a variable using pointer in C++?
Write a program to declare two integer , one float variables and assign 10, 15, and 12.6 to them respectively. It then prints these values on the screen.
What is a Variable?
What is an algorithm (in terms of the STL/C++ standard library)?
what are auto static variables and auto extern variables?
How many ways are there to initialize an int with a constant?
How do you decide which integer type to use?
How is static variable stored in the memory?( if there are 2 functions in a file,and the static variable name is same (ex var) in both the function. how is it keep seperately in the memory).
What can I safely assume about the initial values of variables which are not explicitly initialized?
What?s the auto keyword good for?
What is the difference between declaration and definition?
How variable declaration in c++ differs that in c?
What is difference between followin intialization.int iVar1;int iVar2 = int();and which one of two should we prefer always and why?
Are private class-level variables inherited?
Are there any new intrinsic (built-in) data types?
I was trying to use an "out int" parameter in one of my functions. How should I declare the variable that I am passing to it?
When you inherit a protected class-level variable, who is it available to?
What is a node class in c++?
What is the difference between an external iterator and an internal iterator? Describe an advantage of an external iterator.
Explain about Variables Data Types ?
Explain about Fundamental data types ?
Explain about Declaration of variables ?
