Convert an integer to its alpha-numeric equivalent represented as a null terminated string

ConvertAnIntToString.txt

Write a function that converts an int into its alpha-numeric equivalent represented as a null terminated string. 
The function should accept an int as input and return a string as output. For instance, calling the function with 
an int value of 324 would return a null terminated string containing "324". Ensure that your function checks for 
appropriate boundary conditions and edge cases. Assume you cannot use any standard libraries (for example, no itoa or sprintf).

// Let me spend first 10 minutes to model this question 
// Convert an int to alpha-numeric string 
// let me think about module function 324%10=4, we get first digit, but in reverse order; continue, %10, get second 
// digit, 324/10 as int, which is 2; and continue, 3/10, get three; now 432, reverse order; 
// boundary case:  negative int, 0, -,+ sign discussion +123, out put 123; -123 output -123
// edge case: last char is '\0', think about possible edge case: first char, last char
// Leave blank:
// aplha-numeric equivalent

//string convertToString(int n)
char[] convertToString(int n)
{
    //since int maximum size is known, so we can declare an array to store ouput
   // char[] output = new char[100]; 
   int [] output = new int[100]; // int 100, may be small one 
    
    if(n==0)
    return "0"; 
    // more edge case
    bool isPositive = true; 
    if(n<0)
    {
        n=-n;
        isPositive = false;   // -100 
    }
    // at least I have one edge case, continue later. need idea?
    
    
    int count=0; 
    int loopInt = n; 
    // go over a test case manually, 324 
    for(;;)
    {
        int digitOne = loopInt%10;   // first one, 4; 32; 3, digitOne=3
        
        output[count] = digitOne;    // output[0]=4, output[1]=2, output[2]=3
        
        count++;   // fist time count=1; count =2; count=3
        int newLookInt = loopInt/10;  // first time, 32; 3; 
        
        loopInt = newLookInt; // play safe, late optimize the code // first time 32; 3
        
        if(newLookInt==0)   // 32 (1); 3
            break;   // break the loop, avoid dead loop
    }
    
    // output[100]  4, 2, 3   count =3 
    //  cannot use standard libraries, so I have to convert 1 to 1, ascill code? relax the requirement
    // since I did some math here using % 
    /*
    string outputStr="";
    if(!isPositive)
        outputStr = "-";
        
    for(int i=0;i<count;i++)
    {
        outputStr += output[count-i-1].tostring(); // at least one digit
    }
    */
    char[] outputStr = new char[100]; 
    int startPos = 0; 
    if(!isPositive)
    {
        outputStr[0] = "-";
        startPos = 1; 
    }
        
    for(int i=0;i<count;i++)
    {
        //outputStr += output[count-i-1].tostring(); // at least one digit
        // play safe, I cannot recall the ascill function etc. 
        int currentIndex = count-i-1; 
        if(output[currentIndex] == 0)
            outputStr[startPos] = '0';
        if(output[currentIndex] == 1)
            outputStr[startPos] = '1';
        if(output[currentIndex] == 2)
            outputStr[startPos] = '2';
        if(output[currentIndex] == 1)
            outputStr[startPos] = '3';
        if(output[currentIndex] == 4)
            outputStr[startPos] = '4';
        if(output[currentIndex] == 5)
            outputStr[startPos] = '5';
        if(output[currentIndex] == 6)
            outputStr[startPos] = '6';
        if(output[currentIndex] == 7)
            outputStr[startPos] = '7';
        if(output[currentIndex] == 8)
            outputStr[startPos] = '8';
        if(output[currentIndex] == 9)
            outputStr[startPos] = '9';
            
        startPos ++; 
    }
    
    outputStr[startPos]=null; // null terminal string
    
    return outputStr; 
    // review time, possible problems:
    // null terminal string, I am using C#; ? check point 1
    // I think my 1 hour time limit is reached. Thanks you for the opportunity to be considered. I like this format
    // Wish me good luck
    
}