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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. bool isValid(string str, int n)
  4. {
  5.  
  6. 	if (!((str[0] >= 'a' && str[0] <= 'z')
  7. 		|| (str[0] >= 'A' && str[0] <= 'Z')
  8. 		|| str[0] == '_'))
  9. 		return false;
  10.  
  11.  
  12. 	for (int i = 1; i < str.length(); i++) {
  13. 		if (!((str[i] >= 'a' && str[i] <= 'z')
  14. 			|| (str[i] >= 'A' && str[i] <= 'Z')
  15. 			|| (str[i] >= '0' && str[i] <= '9')
  16. 			|| str[i] == '_'))
  17. 			return false;
  18. 	}
  19.  
  20.  
  21. 	return true;
  22. }
  23.  
  24. int main()
  25. {
  26. 	string str = "geeks123";
  27. 	int n = str.length();
  28.  
  29. 	if (isValid(str, n))
  30. 		cout << "Valid";
  31. 	else
  32. 		cout << "Invalid";
  33.  
  34. 	return 0;
  35. }
Success #stdin #stdout 0.01s 5280KB
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Standard input is empty
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Valid
https://ideone.com/e8x515
language:
C++ (gcc 8.3)
created:
5 days ago
visibility:
public

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