How do you add a char at the end of a string?

I have a code where it says if it has an odd number of chars, add a random char A-Z heres the code for that:

Code:

if(strlen(message) % 2 == 1) 
	{	while(message[i] != '\0')
		{	i++;
		}
		message[i] = char((rand() % 26) + 65);
	}

When I display that string, it gives me the chars I entered along with the random one but this is what comes out... ABC is the message i entered and R is the random char... I dont know what the other stuff is. This only happens when I add a character.

A B C R ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠ ╠
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If you need it here is the entire function...

Code:

void main()
{
	int d = 157, n = 2773, e = 17, i = 0, encoded[100];
	char message[50];

	srand(time(NULL));

	for(int trash = 0; trash <= 10; trash++)
		rand();
	

	cout<<"Enter a message (no spaces): ";
	cin>>message;
	cout<<"You entered: "<<message<<endl;
	
	if(strlen(message) % 2 == 1) 
	{	while(message[i] != '\0')
		{	i++;
		}
		message[i] = char((rand() % 26) + 65);
	}
	display(message);

}

And here is the function I use to display the string:

Code:

void display(char m[])
{	int i = 0;
	while(m[i] != '\0')
	{	cout<<m[i]<<" ";
		i++;
	}
}

The int variables are for later in the program so they dont mean anything now, including the encoded[] array.

Code:

message[i] = char((rand() % 26) + 65);//overwriting here

What you are doing is overwriting the '\0' terminator after the ABC with R, so it's no more a string but simply a chunk of characters, and when you display it, with the condition m[i]!='\0', it gives you random chars as no '\0' is found.

Originally Posted by BEN10

Code:

message[i] = char((rand() % 26) + 65);//overwriting here

What you are doing is overwriting the '\0' terminator after the ABC with R, so it's no more a string but simply a chunk of characters, and when you display it, with the condition m[i]!='\0', it gives you random chars as no '\0' is found.

Thank you!

I changed the code to

Code:

if(strlen(message) % 2 == 1) 
	{	while(message[i] != '\0')
		{	i++;
		}
		message[i] = char((rand() % 26) + 65);
		message[i + 1] = '\0';
	}

and it worked perfectly!

Use std::string instead. It can append characters using +=.
And don't use void main! SourceForge.net: Void main - cpwiki

Code:

char((rand() % 26) + 65)

Change to:

Code:

char((rand() % 26) + 'A')

And use std::string as Elysia suggested. What you have will only work until someone overflows your buffer. std::string will avoid this, and it'll be easier to code with.