strtol()

convert a string to a long integer

Synopsis:

#include <stdlib.h>

long int strtol( const char *ptr,
                 char **endptr,
                 int base );

Description:

The strtol() function converts the string pointed to by ptr to an object of type long int. It recognizes a string containing:

• optional white space,
• an optional plus or minus sign,
• a sequence of digits and letters.

The conversion ends at the first unrecognized character. A pointer to that character will be stored in the object to which endptr points, if endptr is not NULL.

If base is zero, the first characters after the optional sign determine the base used for the conversion. If the first characters are 0x or 0X the digits are treated as hexadecimal. If the first character is 0, the digits are treated as octal. Otherwise the digits are treated as decimal.

If base is not zero, it must have a value between 2 and 36. The letters a-z and A-Z represent the values 10 through 35. Only those letters whose designated values are less than base are permitted. If the value of base is 16, the characters 0x or 0X may optionally precede the sequence of letters and digits.

Returns:

The converted value. If the correct value would cause overflow, LONG_MAX or LONG_MIN is returned according to the sign, and errno is set to ERANGE. If base is out of range, zero is returned and errno is set to EDOM.

Examples:

#include <stdlib.h>

void main()
  {
    long int v;

    v = strtol( "12345678", NULL, 10 );
  }

Classification:

ANSI

See also:

atoi(), atol(), errno, itoa(), ltoa(), sscanf(), strtoul(), ultoa(), utoa()