NAME

atof, atoi, atol − convert ASCII to numbers

SYNOPSIS

#include <math.h>

double atof(nptr)
char ∗nptr;

atoi(nptr)
char ∗nptr;

long atol(nptr)
char ∗nptr;

DESCRIPTION

These functions convert a string pointed to by nptr to floating, integer, and long integer representation respectively.  The first unrecognized character ends the string. 

atof recognizes an optional string of spaces, then an optional sign, then a string of digits optionally containing a decimal point, then an optional ‘e’ or ‘E’ followed by an optionally signed integer. 

atoi and atol recognize an optional string of spaces, then an optional sign, then a string of digits. 

SEE ALSO

scanf(3S)

DIAGNOSTICS

atof clears errno when no errors are encountered.  If the exponent of the number pointed to by nptr is excessively large, atof will set errno to ERANGE and will return MAXDOUBLE .  If the exponent is not legitimate, atof will set errno to ERANGE and will return zero. 

BUGS

There are no provisions for overflow. 

7th Edition