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++.
- All the valid identifiers should either start with alphabet or underscore (_).
- 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
*/
#include
#include
#include
#include
using namespace std;
int main()
{
char str[100];
int i;
int valid = 1; // for checking validity
//input phase
cout<<"\n Enter any identifier :";
cin.getline(str,100);
//processing phase
cout<<"\n Entered Identifier :"<<str;
if(isalpha(str[0])||str[0]=='_')
valid = 1;
else
valid = 0;
if(valid==1)
{
for(i=1;i<strlen(str);i++)
{
if(!(isalpha(str[i]) || isdigit(str[i])|| str[i]=='_'))
{valid = 0; break;}
}
}
//output phase
if(valid == 0 )
cout<<"\n Invalid identifier";
else
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.
