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c语言isalnum()函数的用法介绍判断字符是否为英文或数字，c语言函数汇总有哪些？isalnum()函数要引入什么头文件？返回值是什么？

isalnum()头文件：#include

定义函数：int isalnum(int c);

isalnum()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。

isalnum()应用实例源码：找出str 字符串中为英文字母或数字的字符。

#include

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]);

}

函数实例执行结果：

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