In C, why is sizeof(char) 1, when 'a' is an int?

c size char int sizeof
legends2k picture legends2k · Feb 12, 2010 · Viewed 23k times · Source

I tried

printf("%d, %d\n", sizeof(char), sizeof('c'));

and got 1, 4 as output. If size of a character is one, why does 'c' give me 4? I guess it's because it's an integer. So when I do char ch = 'c'; is there an implicit conversion happening, under the hood, from that 4 byte value to a 1 byte value when it's assigned to the char variable?

Answer

Richard Pennington picture Richard Pennington · Feb 12, 2010

In C 'a' is an integer constant (!?!), so 4 is correct for your architecture. It is implicitly converted to char for the assignment. sizeof(char) is always 1 by definition. The standard doesn't say what units 1 is, but it is often bytes.

Related questions

How can I get a file's size in C?

How can I find out the size of a file I opened with an application written in C ? I would like to know the size, because I want to put the content of the loaded file into a string, which …

Read More
Determine size of dynamically allocated memory in C

Is there a way in C to find out the size of dynamically allocated memory? For example, after char* p = malloc (100); Is there a way to find out the size of memory associated with p?

Read More
How does free know how much to free?

In C programming, you can pass any kind of pointer you like as an argument to free, how does it know the size of the allocated memory to free? Whenever I pass a pointer to some function, I have to …

Read More