finding size of char*

I have been struggling for a long time trying different sizeof algorithms ive made up to find out how many objects are in the array. How can i do this??? I used sample code from charlez petzolds book and i have used the same algorithm and it works in his but not mine. so please help.

for finding the size of a char, include the string.h or cstring lib and use the function:

Code:

int strlen(const char *string);

example

Code:

char string[30] = "Hello World";
cout<<"The char is "<<strlen(string)<<" characters long"<<endl;

Originally Posted by JoshR

I have been struggling for a long time trying different sizeof algorithms ive made up to find out how many objects are in the array. How can i do this??? I used sample code from charlez petzolds book and i have used the same algorithm and it works in his but not mine. so please help.

basiclly you cant' in most of the times..

Code:

char b[10];
sizeof(b) returns sizeof(char) which is 1 times 10

int f(char b[]){return sizeof(b);}
f(b) returns sizeof(char*) because only a pointer is passed, and not the whole array.

char *c = new char[10];
sizeof(c) returns sizeof(char*), usually a 32 bits memory adress

So you'll have to keep track of the number of elements stored.

thanks a lot ay_okay

1) When you declare an array, you have to know the size to begin with. For instance,

Code:

const int size = 3;
double myArray[size] = {1.5, 2.5, 3.5};
cout<<"The size of the array is: "<<size<<endl;

If you want to send the array to a function and inside the function you need to know the size, then you should define the function to also accept the size of the array. For instance,

Code:

void myFunc(double anArray[], int size)
{
	for(int i = 0; i<size; i++)
	{
		cout<<anArray[i]<<endl;
	}
}

2) If you insist on using sizeof to get the size of the array, you can use an expression like this:

sizeof arrayName/sizeof arrayName[0]

For instance,

Code:

#include <iostream>
using namespace std;

class Apple
{
public:
	int weight;
};

int main ()
{
	const int size = 3;
	Apple appleArray[size];
	
	for(int i = 0; i < sizeof appleArray/sizeof appleArray[0]; i++)
	{
		appleArray[i].weight = i+1;
	}

	for(i= 0; i < sizeof appleArray/sizeof appleArray[0]; i++)
	{
		cout<<appleArray[i].weight<<endl;
	}

	return 0;
}