Atof Atoi Atol ASCII to number conversions double atof char *ptr long atol char *ptr int atoi char *ptr Conversions of the string pointed to by "ptr" to the relevant number type are carried out by these functions. They cease to convert a number when the first unrecognized character is encountered. Each skips leading spaces and tab characters. Atof() recognizes an optional sign followed by a digit string that could possibly contain a decimal point, then an optional "e" or "E", and optional sign and a digit string. Atol() and atoi() recognize an optional sign and a digit string. Overflow causes unpredictable results. There are no error indications.