8. C language variable declaration and definition


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If you want to practice this skill, you have to obey your own naming rules, whether it is C language or C + + or other programming languages, you must abide by your own naming rules, so that you can be correctly recognized and compiled by the compiler!



When defining a variable, the variable name can be a combination of letters, numbers, and underscores. However, it is not a random combination. We should pay attention to the following naming rules:

1) Variable names must begin with letters or underscores, not numbers. In practical programming, the most commonly used is to start with a letter, and the variable name starting with an underline is system specific. In programming, never use an underline as the beginning of a variable name unless it is required to do so;

Int 8A = 0; // wrong writing
Int a = 0; // correct writing



2) Letters in variable names are case sensitive. For example, a and a are different variable names, and num and num are also different variable names;


//Define two variables, Num num num, and initialize them to 0 
int num = 0;
int Num = 0;



3) The variable name must not be a C language keyword, this must be remembered! Therefore, in order to avoid conflicts with system defined names;

Int int = 0; // wrong writing method: int is the keyword shaped by C language
Int float = 0; // wrong writing method: float is the keyword of C language floating point number



4) Variable names cannot have spaces. This can be understood as follows: as we said above, the variable name is a combination of letters, numbers and underscores. There is no space item;


Int a B = 0; // wrong writing
Int AB = 0; // correct writing



For detailed nomenclature, see: C / C + + variable naming – Hungarian nomenclature



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1. Install visual studio 2015

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3. Set visual studio font / background / line number

4. Completely uninstall Visual Studio 2008

5. Completely uninstall visual studio 2013 / 2015


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