...isalnum  
 
 
 

isalnum(测试字符是否为英文或数字)
相关函数 isalpha,isdigit,islower,isupper
表头文件 #include<ctype.h>
定义函数 int isalnum (int c)
函数说明 检查参数c是否为英文字母或阿拉伯数字,在标准c中相当于使用
“isalpha(c) || isdigit(c)”做测试。
返回值 若参数c为字母或数字,则返回TRUE,否则返回NULL(0)。
附加说明 此为宏定义,非真正函数。
 

 
 

                                Linhan 2005 ShenZhen
 

范例:

/* 找出str 字符串中为英文字母或数字的字符*/
#include < ctype.h>
main()
{
char str[]=”123c@#FDsP[e?”;
int i;
for (i=0;str[i]!=0;i++ )
if ( isalnum(str[i])) printf(“%c is an alphanumeric
character\n”,str[i]);
}
执行 1 is an apphabetic character
2 is an apphabetic character
3 is an apphabetic character
c is an apphabetic character
F is an apphabetic character
D is an apphabetic character
s is an apphabetic character
P is an apphabetic character
e is an apphabetic character