Str2Num

Safe conversions for C/C++ style string to numbers

Why do I need this?

C++ style string to number conversions throw exceptions. Take a look at the following example:

string s = "\t\r\n\f\v";   
int i = stoi(s);
Since the string is not a number, the stoi function throws an exception `invalid_argument`.

Functions

Function	Supported Language	Description
str2int	C/C++	Converts a string to an integer
str2uint	C/C++	Converts a string to an unsigned integer
str2l	C/C++	Converts a string to a long integer
str2ul	C/C++	Converts a string to an unsigned long integer
str2ll	C/C++	Converts a string to a long long integer
str2ull	C/C++	Converts a string to an unsigned long long integer
str2f	C/C++	Converts a string to a float
str2d	C/C++	Converts a string to a double
safe_stoi	C++	Exception free wrapper for stoi
safe_stol	C++	Exception free wrapper for stol
safe_stoul	C++	Exception free wrapper for stoul
safe_stoll	C++	Exception free wrapper for stoll
safe_stoull	C++	Exception free wrapper for stoull
safe_stof	C++	Exception free wrapper for stof
safe_stod	C++	Exception free wrapper for stod

Notes about C++ only functions (start with safe_):

• Functions are exception free.
• Return value is either std::nullopt or the converted value.
  • If the conversion fails, the return value is std::nullopt.
  • If the conversion succeeds, the return value is the converted value.
• Function parameters are as follows: std::optional<> function(const T& str, std::size_t* pos = nullptr, int base = 10)
  • str is the string to convert, can be std::string or std::wstring only
  • pos if not null, the function also sets the value of idx to the position of the first character in str after the number
  • base is the base of the number, default is 10

Notes about C/C++ only functions (start with str2):

• Functions are exception free and return an error or success code.
• Function parameters are as follows: str2num_errno function(<intergral_type> *out, const char *s, char** endptr , int base)
  • out Pointer to the integeral type to store the result in, ex: int, float, double, etc.
  • s C-style string to convert.
  • endptr Pointer to a pointer to the character after the last character of the string. If the conversion was successful, this will point to the character after the last character of the converted integer.
  • base Base of the number, default is 10.
  • str2num_errno error code returned by the function.

Examples

Safe conversions for C++

std::string s = "123";
auto i = s2n::safe_stoi(s);
// i == 123 if s is a valid integer
// or i  == std::nullopt if s is not a valid integer

Safe conversions for C/C++

char s[] = "123";
int i = 0;
if( str2int(&i, s) == STR2NUM_SUCCESS){
    // i == 123
};
else{
    // Conversion failed, i == 0
};

Extended examples are included in the examples directory.