isalpha() function checks whether a character is an alphabet or not. Alphabet characters include lowercase letters(a-z) and uppercase letters(A-Z).
Function prototype of isalpha
int isalpha(int c);
Function isalpha takes a character as input in form of an integer. When we pass a value of type char to isalpha function, corresponding ASCII value of that character is passed.
Return value of isalpha
If passed character is an alphabet, then isalpha function returns non-zero integer otherwise 0.
C program to show the use of isalpha function
The following program is to check whether a character is alphabet or not.
#include <stdio.h>
#include <ctype.h>
int main(){
char string[] = "Aa1@; .0";
int index = 0;
while(string[index] != '\0'){
if(isalpha(string[index])){
printf("'%c' is alphabet\n", string[index]);
} else {
printf("'%c' is not alphabet\n", string[index]);
}
index++;
}
return 0;
}
Program Output
'A' is alphabet 'a' is alphabet '1' is not alphabet '@' is not alphabet ';' is not alphabet ' ' is not alphabet '.' is not alphabet '0' is not alphabet