char to int64 conversion

Hi, I'm converting a C program that I made using the Visual Studio. I now use GCC (over Linux) and can't find some equivalences. I changed my __int64 definitions to unsigned long long, but can't find an equivalent to the microsoft i64toa() function, which let you convert a char* to a 64 bit integer.

Thanks

char  *litoa(char *dest,long long src)
{
    sprintf(dest,"%ll",src);
    return dest;
}