C++

Reference

<cstdlib> (stdlib.h)

function
<cstdlib>

strtoull

unsigned long long int strtoull (const char* str, char** endptr, int base);
Convert string to unsigned long long integer
Parses the C-string str interpreting its content as an integral number of the specified base, which is returned as a value of type unsigned long long int. If endptr is not a null pointer, the function also sets the value of endptr to point to the first character after the number.

This function operates like strtol to interpret the string, but produces numbers of type unsigned long long int (see strtol for details on the interpretation process).

Parameters

str
C-string beginning with the representation of an integral number.
endptr
Reference to an object of type char*, whose value is set by the function to the next character in str after the numerical value.
This parameter can also be a null pointer, in which case it is not used.
base
Numerical base (radix) that determines the valid characters and their interpretation.
If this is 0, the base used is determined by the format in the sequence (see strtol for details).

Return Value

On success, the function returns the converted integral number as an unsigned long long int value.
If no valid conversion could be performed, a zero value is returned (0ULL).
If the value read is out of the range of representable values by an unsigned long long int, the function returns ULLONG_MAX (defined in <climits>), and errno is set to ERANGE.

Example

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/* strtoull example */
#include <stdio.h>      /* printf, NULL */
#include <stdlib.h>     /* strtoull */

int main ()
{
  char szNumbers[] = "250068492 7b06af00 1100011011110101010001100000 0x6fffff";
  char * pEnd;
  unsigned long long int ulli1, ulli2, ulli3, ulli4;
  ulli1 = strtoull (szNumbers, &pEnd, 10);
  ulli2 = strtoull (pEnd, &pEnd, 16);
  ulli3 = strtoull (pEnd, &pEnd, 2);
  ulli4 = strtoull (pEnd, NULL, 0);
  printf ("The decimal equivalents are: %llu, %llu, %llu and %llu.\n", ulli1, ulli2, ulli3, ulli4);
  return 0;
}

Output:

The decimal equivalents are: 250068492, 2064035584, 208622688 and 7340031.


Data races

The array pointed by str is accessed, and the pointer pointed by endptr is modified (if not null).

Exceptions (C++)

No-throw guarantee: this function never throws exceptions.

If str does not point to a valid C-string, or if endptr does not point to a valid pointer object, it causes undefined behavior.

See also

strtoul
Convert string to unsigned long integer (function)
atol
Convert string to long integer (function)
strtoll
Convert string to long long integer (function)
strtod
Convert string to double (function)