char[]

[Sneeden]

I am using a low level c compiler for PIC. There are no string libs. I don't know how to handle char[]. For example, I wrote a function, PrintChar(char iChar); that prints a single char to an LCD. How can I pass a char[] and print the whole string instead of a single char without str functions? I am not quit sure how to loop through the char[]. If someone could post examples or links that would be great. thx

[sunburnt]

void PrintChar(const char* szText)
{
	// as long as szText is not pointing to a null char
	while ( szText != '\0' )
	{
		// print the current character
		// and move the pointer to the next one
		PrintChar( (*szText++) );
	}
}

or you could pass in the length of the string:

void PrintChar(const char* szText, int length)
{
	for(int i = 0; i < length; ++i)
		PrintChar(szText[i]);
}

[Darkwraith]

How low is this C complier? If you are able to do assembler, there is a quick way to machine-gun a string to display (sorry, 80x86 assembler):

http://burks.brighton.ac.uk/burks/la...smtut/asm8.htm

You could include chunks like this if you use the asm keyword.

[Sneeden]

Hey thanks. Here is what it ended up being. The compiler is picky so I had to put ++ operator in a different place. It works though.

const char *hello="hello";

PrintStr(hello);

void PrintStr(const char *iChar)
{
	uns8 x=0;
	while(iChar[x]!='\0')
	{
		PrintChar(iChar[x++]);
	}
}:w

[Sneeden]

Thx anyways Darkwraith. The compiler does allow for inline asm commands, but I wanted to stick to c. BTW, the proc is a PIC 18F877 (The asm code is quit different from 8086.)

Thanks for the quick help guys

[Sneeden]

One more question. Why is it necessary for the char[] to be const? I first tried writing it with a var, but the compiler does not allow for it, and all example I have seen also use const. It would save me some memory by using a var. I only have 8k of program memory, so every little bit helps.

[Darkwraith]

Will it let allow you write it as:

char hello[] = "hello";

?

[Sneeden]

I tried:
char test[]="test";
the compiler says "array size required"

then I tried:
char test[20]="test";
the compiler says "static const is needed"

then I tried
char *test="test";
the comiler says "const * type modifier is required

It appears like it won't let me use a variable, just constants. This can't be the only solution can it?

[Darkwraith]

My solution works with g++. I don't know what the compiler will allow you to use, though.

If you could give me a link to the compiler that you are using, I could take a look and see if there are any alternative syntaxes.

[Sneeden]

Here is a link to the compiler.
http://www.bknd.com/cc8e/index.shtml

The only examples I saw all used const. I am going to send him an email. He is usually good about answering questions.

[parksie]

Any string in double quotes in your source file will be produced as a constant when compiled. In some cases they may end up in read-only memory.

[sunburnt]

A good reason for the above is that if in several different places in your code, you use a string literal the compiler doesn't have to place it in your executable N times; it can just place it there once and then all instances of that string literal will point to the same place in memory.

[Sneeden]

parksie was correct. I contacted the author. This compiler ends up placing the stings in ROM, and this compiler's pointers can only point to ROM (can't point to RAM).