C library functions - isalnum ()

C standard library - <ctype.h>

description

C library functionsvoid isalnum (int c) Check whether the character is preaching letters and numbers.

statement

Here is () statement isalnum function.

int isalnum(int c);

parameter

• c - This was a test of character.

return value

If c is a number or a letter, the function returns a nonzero value, otherwise return 0.

Examples

The following example demonstrates isalnum () function is used.

#include <stdio.h>
#include <ctype.h>

int main()
{
   int var1 = 'd';
   int var2 = '2';
   int var3 = '\t';
   int var4 = ' ';
    
   if( isalnum(var1) )
   {
      printf("var1 = |%c| 是字母数字\n", var1 );
   }
   else
   {
      printf("var1 = |%c| 不是字母数字\n", var1 );
   }
   if( isalnum(var2) )
   {
      printf("var2 = |%c| 是字母数字\n", var2 );
   }
   else
   {
      printf("var2 = |%c| 不是字母数字\n", var2 );
   }
   if( isalnum(var3) )
   {
      printf("var3 = |%c| 是字母数字\n", var3 );
   }
   else
   {
      printf("var3 = |%c| 不是字母数字\n", var3 );
   }
   if( isalnum(var4) )
   {
      printf("var4 = |%c| 是字母数字\n", var4 );
   }
   else
   {
      printf("var4 = |%c| 不是字母数字\n", var4 );
   }
	
   return(0);
}

Let's compile and run the above program, which will result in the following:

var1 = |d| 是字母数字
var2 = |2| 是字母数字
var3 = | | 不是字母数字
var4 = | | 不是字母数字

C standard library - <ctype.h>