isalnum() - C函數

C庫函數 void isalnum(int c)檢查，傳遞的字符字母是否爲數字。

聲明

以下是isalnum（）函數的聲明。

int isalnum(int c);

參數

• c -- 這是要檢查的字符。

返回值

這個函數返回非零值，如果c是一個數字或字母，否則爲0

實例

下面的例子顯示isalnum（）函數的用法。

#include <stdio.h> #include <ctype.h> int main() { int var1 = 'd'; int var2 = '2'; int var3 = ' '; int var4 = ' '; if( isalnum(var1) ) { printf("var1 = |%c| is alphanumeric
", var1 ); } else { printf("var1 = |%c| is not alphanumeric
", var1 ); } if( isalnum(var2) ) { printf("var2 = |%c| is alphanumeric
", var2 ); } else { printf("var2 = |%c| is not alphanumeric
", var2 ); } if( isalnum(var3) ) { printf("var3 = |%c| is alphanumeric
", var3 ); } else { printf("var3 = |%c| is not alphanumeric
", var3 ); } if( isalnum(var4) ) { printf("var4 = |%c| is alphanumeric
", var4 ); } else { printf("var4 = |%c| is not alphanumeric
", var4 ); } return(0); }

讓我們編譯和運行上面的程序，這將產生以下結果：

var1 = |d| is alphanumeric
var2 = |2| is alphanumeric
var3 = | | is not alphanumeric
var4 = | | is not alphanumeric