Char array length function - c++

Question

Does anyone know how to write a function that counts length of an array given like in example ?
cout << length(argv[1]) << endl;
I've tried somethig like this but it says that there can't be function lentgh then.
for(int i = 0; myStrChar[i] != '\0'; i++)
{
count++;
}
EDIT1: Here is the rest of code :
#include <iostream>
#include<cstring>
using namespace std;
int i;
int length()
{
for(int i = 0; myStrChar[i] != '\0'; i++)
{
count++;
}
}
int main()
{
cout << "Hello world!" << endl;
cout << "length of first text: ";
cout << length(argv[1]) << endl;
char tab[255] = {"Ana has a cat"};
EDIT2: Now I did something like this but it puts out 108 as length of text
char argv[]="ana has a cat";
int length(char l)
{
int cou= 0;
for(int i = 0; i!=0; i++)
{
cou++;
return cou;
}
}

Answer 1

Hmm, what's wrong? It is a valid code - just wrap it into a function:
size_t length(const char* myStrChar)
{
size_t count = 0;
for(int i = 0; myStrChar[i] != '\0'; i++) {
count++;
}
return count;
}
You can do it a bit shorter:
size_t length(const char* myStrChar)
{
size_t count = 0;
for (; myStrChar[count] != 0; count++)
/* Do nothing */;
return count;
}
UPD:
Here is a code from the question and my comments to author:
// You're passing just a single character to this function - not array
// of char's - not a string.
// Pass char* or better const char*.
int length(char l)
{
int cou= 0;
// Ok, this loop does nothing - it's going to stop at the
// first condition check, because you assign 0 to i
// and immediately check if it is not zero - this check will
// return false and the loop will never start.
// Check the current symbol in string if it is not zero
for(int i = 0; i!=0; i++)
{
cou++;
// Even if you'll fix mistakes above, your loop will stop
// at the first iteration, because of this return.
// You must put it right after the loop.
return cou;
}
// Your function actually returns nothing, because no iterations
// of the loop above is performed - so no return statement reached
// at all - it is undefined behaviour :(
// Put return here out of the loop;
}