strspn&strcspn

Posted 2020-06-23 yuxi_o

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

strspn返回s中第一个不在accept中出现过的字符下标。

Returns an integer value specifying the length of the substring in str that consists entirely of characters in strCharSet.

If str begins with a character not in strCharSet, the function returns 0.

accept可以包含多个字符，从str开始搜索，计算str中包含的accept中任一字符的下标。

#include <string.h>
#include <stdio.h>
main()
{
    char *str="Linux was first developed for 386/486-based pcs.";
    printf("%d\n",strspn(str,"Linux"));
    printf("%d\n",strspn(str,"/-"));
    printf("%d\n",strspn(str,"1234567890"));
}

运行结果：

5

0

0

 

size_t strcspn(const char *s, const char * reject);

strcspn()从参数s 字符串的开头计算连续的字符, 而这些字符都完全不在参数reject 所指的字符串中.

简单地说, 若strcspn()返回的数值为n, 则代表字符串s 开头连续有n 个字符都不含字符串reject 内的字符.

返回字符串s 开头连续不含字符串reject 内的字符数目。

#include <string.h>
 
main(void)
 
{
 
    char *str = "Linux was first developed for 386/486-based pcs. ";
 
    printf("%d\n", strcspn(str, " "));
 
    printf("%d\n", strcspn(str, "/-"));
 
    printf("%d\n", strcspn(str, "1234567890"));
 
}
 

运行结果：

5

33

30