strtoul() function in C/C++

The strtoul() function in C/C++ which converts the initial part of the string in str to an unsigned long int value according to the given base, which must be between 2 and 36 inclusive, or be the special value 0. This function discard any white space characters until the first non-whitespace character is found, then takes as many characters as possible to form a valid base-n unsigned integer number representation and converts them to an integer value.

Syntax:  

unsigned long int strtoul(const char *str, char **end, int base)

Parameter: The function accepts three mandatory parameters which are described below:  

• str: Pointer to the null-terminated byte string to be interpreted
• end : Pointer to a pointer to character (Reference to an object of type char*)
• base : Base of the interpreted integer value

Return value: The function returns two value as below:  

• On success, it returns an integer value corresponding to the contents of str.
• If no valid conversion is done, then 0 is returned.

Below programs illustrate the above function:

Program 1:  

The unsigned long integer is : 15124320
String in str is : Geeks For Geeks

Program 2: