Comparison of Isalnum () function and Isalpha () function in C language using _c language

C language Isalnum () function: To determine whether a character is an English letter or a number
header file:

#include <ctype.h>

Isalnum () is used to determine whether a character is an English letter or a number, equivalent to Isalpha (c) | | IsDigit (c), whose prototype is:

  int isalnum (int c);

"Parameter" C is the character you want to detect.

"Return value" if the parameter C is a letter or a number, if C is 0 ~ 9 A ~ z a ~ z returns not 0, otherwise return 0.

Note that isalnum () is a macro definition, not a true function.

"Instance" finds characters in the STR string that are English letters or numbers.

#include <ctype.h>
Main () {
  char str[] = "123c@ #FDsP [E?";
  int i;
  for (i = 0; Str[i]!= 0; i++)
    if (Isalnum (str[i)))
      printf ("%c be an alphanumeric character\n", str[i));

Output results:

1 is a apphabetic character
2 is a apphabetic character 3 is a apphabetic character C is a
apphabetic Char Acter
F is a apphabetic character
D is a apphabetic character S is a apphabetic
character
P is a appha Betic character
E is a apphabetic character

C language Isalpha () function: To determine whether a character is an English letter
header file:

#include <ctype.h>

Isalpha () is used to determine whether a character is an English letter, equivalent to Isupper (c) | | Islower (c), whose prototype is:

  int isalpha (int c);

"Parameter" C is the character that needs to be detected.

return value if parameter C is an English letter (a ~ z a ~ z), returns a value other than 0, otherwise returns 0.

Note that Isalpha () is a macro definition, not a true function.

"Instance" finds characters in the STR string that are English letters.

#include <ctype.h>
Main () {
  char str[] = "123c@ #FDsP [E?";
  int i;
  for (i = 0; Str[i]!= 0; i++)
    if (Isalpha (str[i)))
      printf ("%c be an alphanumeric character\n", str[i));

Execution results:

C is a apphabetic character
F is a apphabetic character D is a apphabetic
character S is a
apphabetic C Haracter
P is a apphabetic character
E is a apphabetic character