Convert a C string to a number

Int atoi (const char * Str) // Convert string to integer
Ignore the white space in front of STR until the first non-white space character is encountered. If the first non-white space character is a plus or minus sign or number, convert as long as possible to a number. If no valid conversion result is returned, 0 is returned. If the converted value exceeds the int value range, int_max or int_min is returned.

 

Long int atol (const char * Str)// Convert string to long integer
Refer to atoi.

 

Long int strtol (const char * nptr, char ** endptr, int Base)// Convert string to long integer
This function converts the nptr parameter to the Growth integer number based on the base parameter. The base parameter ranges from 2 to 36, or 0. The base parameter indicates the base mode. For example, if the base value is 10, the base value is 10. If the base value is 16, the base value is hexadecimal. When the base value is 0, 10 is used for conversion, however, if the '0x 'prefix is used for hexadecimal conversion, and if the '0' prefix is not '0x', the '8' prefix is used for conversion. At the beginning, strtol () scans the nptr parameter string and skips the leading space character until it starts to convert in case of a number or positive or negative sign, when a non-number or string ends ('\ 0'), the conversion ends and the result is returned. If the endptr parameter is not null, the character pointer in the nptr that is terminated due to an exception is returned by the endptr.