Valid IdentifierChecker

Description:

An identifier in C, Java, C++ and most other programming languages must begin with a letter and then may be followed by any number of letters or digits. It is possible that underscores (_) will also appear, but only in the middle and never two consecutively. Write a program to read a string and output whether it is a valid or invalid identifier. Each string will be 10 characters or less in size. Test Case 1 Input (stdin) UAB_HSPC Expected Output valid identifier Test Case 2 Input (stdin) 2ab Expected Output not a valid identifier

Program :

#include<stdio.h>

#include<string.h>

int main()

{

char string[25];

int count=0,flag;

  int i;

scanf ("%[^\n]s",string);

if( (string[0]>='a'&&string[0]<='z')

    ||

    (string[0]>='A'&&string[0]<='Z')

    ||

    (string[0]=='_')

   )

       {

   for(i=1;i<=strlen(string);i++)

   {

     if((string[i]>='a'&& string[i]<='z')

     ||

      (string[i]>='A' && string[i]<='Z')

     ||

     (string[i]>='0'&& string[i]<='9')

     ||

     (string[i]=='-')

     )

     {

 count++;

     }

   }

    if(count==strlen(string))

    {

      flag=0;

    }

  }

 else

 {

  flag=1;

 }


if(flag==1)

 printf("not a valid identifier");

 else

 printf("valid identifier");

return 0;


}