This documentation is copyright © 1998-2001 Sandro Sigala <sandro@sigala.it>.
All rights reserved.

Released under the GNU General Public License.

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strspn

Prototype

#include <string.h>

size_t strspn(const char *s, const char *set);

Description

Returns the length of the maximum initial segment of the string s which consists entirely of characters from the string set.

Implementation

View source
#include <string.h>

size_t strspn(const char *s, const char *set)
{
    const char *sp1, *sp2;

    for (sp1 = s; *sp1 != '\0'; ++sp1)
	for (sp2 = set; ; ++sp2)
	    if (*sp2 == '\0')
		return sp1 - s;
	    else if (*sp1 == *sp2)
		break;

    return sp1 - s;
}

Example

View source
#include <string.h>

/*
 * Return a true value if the argument string is a regular
 * decimal number.
 */
int is_number(const char *s)
{
    if (strspn(s, "0123456789") == strlen(s))
	return 1;
    return 0;
}

References

ISO C 9899:1990 7.11.5.6