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Interesting facts about data-types and modifiers in C/C++
• Difficulty Level : Easy
• Last Updated : 17 Apr, 2020

Here are some logical and interesting facts about data-types and the modifiers associated with data-types:-

1. If no data type is given to a variable, the compiler automatically converts it to int data type.

## C++

 `#include ``using` `namespace` `std;`` ` `int` `main()``{``    ``signed` `a;``    ``signed` `b;`` ` `    ``// size of a and b is equal to the size of int``    ``cout << ``"The size of a is "` `<< ``sizeof``(a) <

## C

 `#include ``int` `main()``{``    ``signed` `a;``    ``signed` `b;`` ` `    ``// size of a and b is equal to the size of int``    ``printf``(``"The size of a is %d\n"``, ``sizeof``(a)); ``    ``printf``(``"The size of b is %d"``, ``sizeof``(b)); ``    ``return` `(0);``}`

Output:
```The size of a is 4
The size of b is 4
```

2. Signed is the default modifier for char and int data types.

## C++

 `#include ``using` `namespace` `std;`` ` `int` `main()``{``    ``int` `x;``    ``char` `y;``    ``x = -1;``    ``y = -2;``    ``cout << ``"x is "``<< x <<``" and y is "` `<< y << endl;``}`` ` `// This code is contributed by shubhamsingh10`

## C

 `#include ``int` `main()``{``    ``int` `x;``    ``char` `y;``    ``x = -1;``    ``y = -2;``    ``printf``(``"x is %d and y is %d"``, x, y);``}`

Output:

```x is -1 and y is -2.
```

3. We can’t use any modifiers in float data type. If programmer tries to use it ,the compiler automatically gives compile time error.

## C++

 `#include ``using` `namespace` `std;``int` `main()``{``    ``signed` `float` `a;``    ``short` `float` `b;``    ``return` `(0);``}``//This article is contributed by shivanisinghss2110`

## C

 `#include ``int` `main()``{``    ``signed` `float` `a;``    ``short` `float` `b;``    ``return` `(0);``}`

Output:
```[Error] both 'signed' and 'float' in declaration specifiers
[Error] both 'short' and 'float' in declaration specifiers
```

4. Only long modifier is allowed in double data types. We cant use any other specifier with double data type. If we try any other specifier, compiler will give compile time error.

## C++

 `#include ``using` `namespace` `std;``int` `main()``{``    ``long` `double` `a;``    ``return` `(0);``}`` ` `// This code is contributed by shubhamsingh10`

## C

 `#include ``int` `main()``{``    ``long` `double` `a;``    ``return` `(0);``}`

## C++

 `#include ``using` `namespace` `std;``int` `main()``{``    ``short` `double` `a;``    ``signed` `double` `b;``    ``return` `(0);``}`` ` `// This code is contributed by shubhamsingh10`

## C

 `#include ``int` `main()``{``    ``short` `double` `a;``    ``signed` `double` `b;``    ``return` `(0);``}`

Output:
```[Error] both 'short' and 'double' in declaration specifiers
[Error] both 'signed' and 'double' in declaration specifiers
```

This article is contributed by Bishal Kumar Dubey. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.