Easy C++ = array length and reverse WITHOUT <string> - c++

Question

I can't seem to get my array's length or to print backwards! ANY HELP PLEASE?!
the functions on the bottom for void GetStringLenght and Print Backwards aren't working
#include <iostream>
void ReadString(char* c, int maxLength);
void GetStringLength(char* c, int* length);
void PrintString(char* const c);
void PrintStringBackwards(char* const c);
int main()
{
const int SIZE = 50;
char ca[SIZE];
char* pc = ca;
int fPrints = 0;
int bPrints = 0;
int lengthChecks = 0;
char selection = 'z';
while (selection != 'Q') {
std::cout << "\n[ 1] Test ReadString\n";
std::cout << "[ 2] Test GetStringLength\n";
std::cout << "[ 3] Test PrintString\n";
std::cout << "[ 4] Test PrintStringBackwards\n";
std::cout << "[Q] Quit\n";
std::cout << "Selection: ";
std::cin >> selection;
std::cin.ignore();
std::cout << std::endl;
switch (selection) {
//Test ReadString
case '1':
ReadString(pc, SIZE);
break;
//Test GetStringLength
case '2': {
lengthChecks += 1;
int length = 0;
GetStringLength(pc, &length);
std::cout << "Length[" << lengthChecks << "]=" << length << std::endl;
break;
}
//Test PrintString
case '3':
fPrints += 1;
std::cout << "Foward[" << fPrints << "]=";
PrintString(pc);
std::cout << std::endl;
break;
//[ 4] Test PrintStringBackwards
case '4':
bPrints += 1;
std::cout << "Backwards[" << bPrints << "]=";
PrintStringBackwards(pc);
std::cout << std::endl;
break;
case 'Q':
break;
default:
break;
} //end switch
} //end while
std::cout << "Press ENTER";
std::cin.get();
return 0;
}
void ReadString(char* c, int maxLength)
{
std::cout << "Enter a string less than " << maxLength << " characters." << std::endl;
std::cin.getline(c, maxLength, '\n');
}
//BELOW THIS DOESNT WORK EITHER///
//////////////////////////////////////////
void GetStringLength(char* c, int* length)
{
for (int i = 0; i < *length; i++) {
if (c[i] == '\0')
*length = i - 1;
}
}
void PrintString(char* const c)
{
int counter = 0;
for (int i = 0; i < 100; i++) {
if (c[i] == '\0') {
counter = i;
break;
} //end if
} //end for
for (int j = 0; j < counter; j++) {
std::cout << c[j];
if (j == counter)
std::cout << '\0';
} //end for
std::cout << std::endl;
} //end void
void PrintStringBackwards(char* const c)
{
//this is where I’m lost! I’ve tried 25 different ways and everything is error.
}

Answer 1

Consider for (int i = 0; i < *length; i++) where both i and *length are 0, as in your case... will that loop ever execute? Nope... Consider a loop that starts with x set to 0 and return x; when str[x] is '\0'. i.e. the loop in strlen does this.
As for printing backwards, start at the highest index (returned by strlen or your function once fixed) and decrement until you reach 0, printing the characters at those offsets as you go.
strlen is available in <cstring>, by the way, not just <string>... and as it is a mandatory function it'll always be part of any C++ implementation. You should probably just use strlen...

Answer 2

To get a C string (char*)'s length you can use strlen(...).
To print backwards, do:
for(int i = strlen(str) - 1; i >= 0; --i)
std::cout << str[i];