How does a String terminate in C?

Question

I know the string in c will be terminated by a character \0.

However, if I do char a[5]="abcd\n" , where would \0 be?

Or do I need to reserve at least one position for \0, whenever I try to use char[] to store a string?

Thank you for any help!

You need to reserve one position for \0. So your array should be a[6]. — kiner_shah
– kiner_shah, Commented Feb 16, 2023 at 8:12
In your code, a is not a string! It's just a static byte buffer of length 5, but it misses the zero termination that would make it a string. C allows this (in C++ this initialisation would be invalid). — Konrad Rudolph
– Konrad Rudolph, Commented Feb 16, 2023 at 8:13
@kiner_shah Thank you, and I was also wondering what will happen if I insist to use a[5]? Can I still normally use functions for string? — cy10
– cy10, Commented Feb 16, 2023 at 8:13
As @KonradRudolph says, the array is not a string in the sense that all standard C string functions expects it to be, because it doesn't have the terminator. So if you pass it to e.g. strlen then you will get undefined behavior. — Some programmer dude
– Some programmer dude, Commented Feb 16, 2023 at 8:15

DanielHsH · Accepted Answer · 2023-02-16 08:19:34Z

3

You should do:

char a[]="abcd\n";

without specifying the size to let compiler figure out the buffer size. The actual buffer will have size of 6 to accommodate your 5 bytes + 1 byte for terminating zero. When you type "something" without assignment, compilaer puts that string in a dedicated place in the program with at least 1 zero byte after the last character.

Writing char a[5]="abcd\n" is a bad practice because it will cause functions like strcpy() to act in undefined manner as your variable 'a' is not a c string, but just a buffer of characters, which by chance seem to be all printable/visible + terminating \n

answered Feb 16, 2023 at 8:19

DanielHsH

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