STRTOUL LIBRARY ROUTINE

Answer

Information in this article applies to:

C166 Version 4.06

QUESTION

What does the strtoul library routine do?

ANSWER

The strtoul library routine converts the contents of a string to an unsigned long. Leading whitespace is ignored. A base may be specified. If the base specified is between 2 and 36, the conversion is performed in that base. If the base specified is zero, the prefix of the value stored in the string determines the base of the conversion: 0 implies an octal value and 0x or 0X implies a hexadecimal value.

This function is declared as follows:

#include <stdlib.h>
unsigned long strtoul (
  const char *string,  /* string to convert */
  char *endp,  /* ptr to unconverted text */
  int base);  /* the base to convert from */

A pointer to the first character in string that can't be converted is stored in endp unless endp is NULL.

For example:

#include <stdlib.h>
#include <stdio.h>

void tst_strtoul (void)  {
  char buf [] = "123456 is a positive number";
  long neck;
  char *p;

  neck = strtoul (buf, &p);
}