CPP program to check valid Identifier

C++ program to check the validity of any input string whether the inputted string is a valid identifier or invalid identifier.  While developing this program we followed the basic rules of a valid identifiers in C/C++.

  1. All the valid identifiers should either start with alphabet or underscore (_).
  2. It should not contain any special character or punctuation marks.

The source code of this program checks these two basic rules.

/*	Program to find out whether an inputed word is a valid identifier or not. 
	made by		: 	rakesh kumar
using namespace std;
int main()
	char str[100];
	int i;
	int valid = 1;   // for checking validity
	//input phase
	cout<<"\n Enter any identifier :";
	//processing phase
	cout<<"\n Entered Identifier :"<<str;
	   valid = 1;
		valid = 0;
	  	   	if(!(isalpha(str[i]) || isdigit(str[i])|| str[i]=='_'))
				{valid = 0; break;}
	//output phase
	if(valid == 0 )
		cout<<"\n Invalid identifier";
		cout<<"\n Valid Identifier";
	return 0;

Above program was developed on Windows 10 Using Dev C++ IDE. The output of valid Identifier program is as follows.

C/C++ program to check validity of given identifier
Identifier validity checker program output

Related Posts

If you like CBSEToaday and would like to contribute, you can also write an article using submit article or mail your article to contribute@cbsetoday.com See your article appearing on the cbsetoday.com main page and help other students/teachers.