adding char * as unsigned int

Please HELP:

This is the declaration of a function that adds together two unsigned integer numbers represented as strings:

void Add(const char * s1, const char * s2, char * result);

The function returns the result in a caller-supplied buffer
assuming that it is always big enough.

E.g. char result[50];

Add(“1273”, “16”, result);

Will return “1289” in the result buffer.

How can I write an implementation of the function in C++ w/o
using atoi(), itoa() or other standard functions for conversion.

Why not use those "char-to-num" or "num-to-char" predefined functions?
It will save you lot of codes.

Here is the code for understanding
void Add(const char * s1, const char * s2, char * result){
int nNum1,nNum2,nResult;
char test[20];
nNum1=atoi(s1);
nNum2=atoi(s2);
nResult=nNum1+nNum2;

itoa(nResult,result,10);


}
How to call

char * result=new char[20];
Add("1273","16",result);

Here is the professional code

void Add(const char * s1, const char * s2, char * result){
itoa(atoi(s1)+atoi(s2),result,10);
}

you can not use any of the standard C library functions that convert from strings to ints. So here is how I would do it:

Code:

---

int ConvertToInt(const char* value)
{
        int n = 0;
        if(value != NULL)
        {
                while(*value != 0)
                        n = (n * 10) + *value++ - '0';
        }
        return n;
}
void Add(const char * s1, const char * s2, char * result)
{

        int i1 = ConvertToInt(s1);
        int i2 = ConvertToInt(s2);
        int i3 = i1 + i2;
        sprintf(result,"%d", i3);

}

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