<ctype.h>头文件中，用于检查传入的字符是否是字母（'A'~'Z' 和 'a'~'z'）或数字（0~9）。int isalnum(int c);
#include <stdio.h>
#include <ctype.h>
int main()
{
char ch;
printf("input a character:"); /*输入一个字符*/
scanf("%c", &ch);
if (isalnum(ch)) { /*判断输入字符是否是字母或数字字符*/
printf("%c is alnum.", ch);
}
else {
printf("%c is not alnmu.", ch);
}
}
运行结果：
input a character:.
. is not alnmu.
#include <stdio.h>
#include <ctype.h>
int main() {
char str[] = "C0ding is fun!";
for(int i = 0; str[i] != '\0'; i++) {
if(isalnum(str[i])) {
printf("'%c' is an alphanumeric character.\n", str[i]);
} else {
printf("'%c' is NOT an alphanumeric character.\n", str[i]);
}
}
return 0;
}
运行结果：
'C' is an alphanumeric character.
'0' is an alphanumeric character.
'd' is an alphanumeric character.
'i' is an alphanumeric character.
'n' is an alphanumeric character.
'g' is an alphanumeric character.
' ' is NOT an alphanumeric character.
'i' is an alphanumeric character.
's' is an alphanumeric character.
' ' is NOT an alphanumeric character.
'f' is an alphanumeric character.
'u' is an alphanumeric character.
'n' is an alphanumeric character.
'!' is NOT an alphanumeric character.
本文链接：http://task.lmcjl.com/news/19108.html