Array assignment for characters: C programming

Question

Need help with array assignment

In my code i am declaring array as shown below.

u8 sendbuffer_1[4];

In my main, i am assigning it as shown below.

sendbuffer_1[] = {":K1\r"};

I tried removing the square brackets as well but doesn't work!!

Get error (with the square brackets)

../src/helloworld.c: In function 'main':
../src/helloworld.c:80:18: error: expected expression before ']' token
sendbuffer_1[] = {":K1\r"};

Error(Without square bracket)

../src/helloworld.c: In function 'main':
../src/helloworld.c:80:20: error: expected expression before '{' token
 sendbuffer_1 = {":K1\r"};

Please let me know the issue. Thanks in advance!!

One too short: you didn't allow for the nul terminator. u8 sendbuffer_1[5] = ":K1\r"; or just u8 sendbuffer_1[] = ":K1\r"; — Weather Vane
– Weather Vane, Commented Apr 9, 2016 at 19:57

Jonathan Leffler · Accepted Answer · 2016-04-09 20:04:14Z

1

You can't assign arrays in C. You can initialize them, but you can't assign them.

This is an initialization:

u8 sendbuffer_1[4] = {":K1\r"};

It wouldn't be legal in C++; it is in C but the sendbuffer_1 array is not null terminated. That's dangerous if you're expecting a string.

Otherwise, you'd use memmove() or something similar to set the array:

memmove(sendbuffer_1, ":K1\r", sizeof(sendbuffer_1));

Beware of the sizes of the source string (":K1\r") and the destination string; the length copied should be the minimum of the two sizes. That is, if sendbuffer_1 was an 80-character buffer, the memmove() would not be safe, not because sendbuffer_1 would be overflowed, but because you'd be accessing beyond the end of the string). Be very careful in C.

edited Apr 9, 2016 at 20:04

answered Apr 9, 2016 at 19:58

Jonathan Leffler

759k145 gold badges961 silver badges1.3k bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Kushal Madane Over a year ago

Thanks a lot!!That

gmoniava Over a year ago

"Be very careful in C" +1.

Ross Meikleham · Accepted Answer · 2016-04-09 20:00:05Z

0

Either when initializing your array:

u8 sendbuffer_1[] = {":K1\r"};

Or if you need to assign these values in your main function you'll need to insert each value individually as follows:

sendbuffer_1[0] = ':';
sendbuffer_1[1] = 'K';    
sendbuffer_1[2] = '1';
sendBuffer_1[3] = '\r';

answered Apr 9, 2016 at 20:00

Ross Meikleham

1641 gold badge1 silver badge9 bronze badges

Collectives™ on Stack Overflow

Array assignment for characters: C programming

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related