isalpha() - ctype.h

The C library function void isalpha(int c) checks if the passed character is alphabetic.
This function returns non-zero value if c is an alphabet, else it returns 0.

Syntax

int isalpha(int c);

Example

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

int main()
{
   int var1 = 'd';
   int var2 = '2';
   int var3 = '	';
   int var4 = ' ';
    
   if( isalpha(var1) )
   {
      printf("var1 = |%c| is an alphabet
", var1 );
   }
   else
   {
      printf("var1 = |%c| is not an alphabet
", var1 );
   }
   
   if( isalpha(var2) )
   {
      printf("var2 = |%c| is an alphabet
", var2 );
   }
   else
   {
      printf("var2 = |%c| is not an alphabet
", var2 );
   }
   
   if( isalpha(var3) )
   {
      printf("var3 = |%c| is an alphabet
", var3 );
   }
   else
   {
      printf("var3 = |%c| is not an alphabet
", var3 );
   }
   
   if( isalpha(var4) )
   {
      printf("var4 = |%c| is an alphabet
", var4 );
   }
   else
   {
      printf("var4 = |%c| is not an alphabet
", var4 );
   }
   
   return(0);
}

Output / Return Value

var1 = |d| is an alphabet                                                   
var2 = |2| is not an alphabet                                               
var3 = |        | is not an alphabet                                        
var4 = | | is not an alphabet

Limitations

Alternatives / See Also

Reference