Thread: error involving char type

A char holds one octet (one byte), And in C double quoted strings means a string (NULL terminated, = more than 1 byte). So In other words you can only fit one byte into quad.

Consider making it a string, not a BYTE... then use strcpy() to fill it.

Code:

char quad[3];
strncpy(quad, "II", sizeof(quad));

http://www.cplusplus.com/reference/c...g/strncpy.html

Just make sure quad is big enough...

I don't know how that compiles. You have more than one major error with it.

First problem is that quad is a char not a char *, which is what you need for this, so that should change. Next, you have wrong conditions. Judging from the type of program, I would venture to say that you're trying to perform a logical AND on both of those conditions, which is done with the && operator (Don't use one & for this. That means something else in C.).

Lastly, you're printing quad out as a numerical value when it should be printed as a string. The format specifier in printf() should be a %s.

So with these changes, as long as a bit of formatting:

Code:

#include <stdio.h>
#include <stdlib.h>

typedef struct
{
	int x;
	int y ;
}POINT;

int main()
{
	POINT ent;
	char *quad;
	printf("\nEnter a point, x variable then y variable\n");
	scanf("%d %d", &ent.x, &ent.y);
	if((ent.x >= 0) && (ent.y >= 0))
	{
		quad = "I";
	}
	else if((ent.x < 0) && (ent.y >= 0))
	{
		quad = "II";
	}
	else if((ent.x < 0) && (ent.y < 0))
	{
		quad = "III";
	}
	else if((ent.x >= 0) && (ent.y < 0))
	{
		quad = "IV";
	}
	printf("Your point is in quadrant: %s \n", quad);
	system("PAUSE");
	return 0;
}

Yeah i fixed the %s issue, i just forgot to change it here. I figured it had something to do with having the wrong type, i just couldnt find it in my book, thanks.

Can someone explain how a pointer to quad fixed that? I get the string suggestion, but not the pointer suggestion.

How about something like this:

First iteration: temp = array[start]; array[start] = array[end]; array[end] = temp;
Second iteration: temp = array[start + 1]; array[start + 1] = array[end - 1]; array[end - 1] = temp;

Etc., until the indexes you're swapping meet each other. Throw it in a loop, and there you go.

Originally Posted by Alphawaves

Can someone explain how a pointer to quad fixed that? I get the string suggestion, but not the pointer suggestion.

When you include a block of letters inside double quotes, that's called a string literal. String literals are usually handled in a special way by your compiler and possibly placed in something like the .data segment of your program.

Remember a string is just a sequence of chars in memory that end with a '\0' char. You can point to this block or memory by pointing to the first element of this block. That's what something like char *ptr = "sometext"; does. "sometext" is stored somewhere in your program, and ptr just points to the first char in the sequence.

The only downside to using a pointer in that manner is that the strings are read-only. Do not alter them. If you wish to alter them, use an array where the strings are copied to that array.

Haha you are a smart one! I didnt really think about setting up two conditions in a for loop.
Thanks for explaining the sting/pointer question.