Why sizeof() return different values when input is (char) and 'A'

Question

I am working on sizeof()

when I entered argument as char data type

J=sizeof(char);

It gives output as 1.

But when I entered argument like this

J=sizeof('A');

I am getting output as 4.

Since it's argument is of char data type it should return 1 as output why it is returning 4/2 (Depending upon 32bit/64bit device).

`sizeof 'A'` will always return 1 in C++. please don't tag random languages in your questions. — Quentin, Apr 10 '18 at 12:34
You tagged this question as both C and C++, but which are you actually using? This is one case where it makes a difference! — aschepler, Apr 10 '18 at 12:34
`c` or `c++`? They are different languages with different rules and most probably you use only one of them at a time. — axiac, Apr 10 '18 at 12:34
Simply check the C Standard or, I hope, any half-decent tutorial that includes a description of literals, and you will understand. — underscore_d, Apr 10 '18 at 12:35
@Quentin thanks for suggestions,new to this place will take care from next time :) — Code Maniac, Apr 10 '18 at 12:38

Bathsheba · Answer 1 · 2018-04-10T13:14:48.300

6

In C, 'A' is not a constant of type char, it is an int type. (In C++ it is a char.)

C is a model of consistency in this respect; cf. C++ where 'a' + 'b' is an int type as is a multicharacter constant like 'ab'.

edited Apr 10 '18 at 13:14

answered Apr 10 '18 at 12:33

Bathsheba

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34
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[Relevant cppreference page](http://en.cppreference.com/w/c/language/character_constant). – Quentin Apr 10 '18 at 12:35

Vlad from Moscow · Answer 2 · 2018-04-10T13:22:11.393

It seems you mean C.

In C character literals (called in C character constants) have type int. So sizeof( 'A' ) is equivalent to sizeof( int ) and yields usually 4.

From the C Standard (6.4.4.4 Character constants)

10 An integer character constant has type int. The value of an integer character constant containing a single character that maps to a single-byte execution character is the numerical value of the representation of the mapped character interpreted as an integer. The value of an integer character constant containing more than one character (e.g., 'ab'), or containing a character or escape sequence that does not map to a single-byte execution character, is implementation-defined. If an integer character constant contains a single character or escape sequence, its value is the one that results when an object with type char whose value is that of the single character or escape sequence is converted to type int.

While sizeof( char ) is alwasy equal to 1.

From the C Standard (6.5.3.4 The sizeof and alignof operators)

4 When sizeof is applied to an operand that has type char, unsigned char, or signed char, (or a qualified version thereof) the result is 1....

@chux Initially the question was marked with C++ tag where the term character literal is used. — Vlad from Moscow, Apr 10 '18 at 13:17
Yes, such C/C++ questions are made more complex than needed. — chux - Reinstate Monica, Apr 10 '18 at 13:25

Why sizeof() return different values when input is (char) and 'A'

2 Answers2